Two layers of choux, filled with vanilla bean pastry cream, a layer of maple brown sugar pecans, and topped with chocolate ganache, this Boston Cream Pie Karpatka is my dream October birthday cake!
What is a Karpatka?
Karpatka is a Polish cake made of two layers of choux pastry filled with a vanilla cream, it reminds me of a giant profiterole or cream puff!
Can I leave out the pecan layer?
Yes! I love the maple brown sugar pecan layer because it cuts the sweetness, adds an extra crunch, and gives it a bit of a fall flavor but you can totally leave it out!
Is Boston Cream Pie a pie?
Boston Cream Pie is actually traditionally a cake and not a pie, it is made of two layers of vanilla cake filled with a pastry cream and topped with chocolate ganache.
Tips for making a Boston Cream Pie Karpatka
- Once you add the flour to the hot butter, water, and salt – stir immediately and forcefully. You need to work the flour into the liquids and cook the raw flour.
- When adding the eggs I recommend first whisking them in a container with a spout – this will make it easier to add the right amount of egg because you won’t always need all of the eggs.
- During the baking process, do not open the oven! You need the steam in the oven to help the choux pastry puff!
- When making the pastry cream, don’t walk away from it – it’s important to keep whisking to prevent the eggs from curdling and keep the starch from clumping.
- It will start to thicken and at first look a little lumpy but it will smooth out as it continues to thicken.
- I love the pecan pie filling layer but if you can’t have nuts or just don’t want it you can absolutely leave it out or swap it with a jam!
- This cake can be a little tricky to cut. I’ve found that the best system is to use a long serrated knife parallel to the top of the cake just to cut through the first layer of choux. Then switch to a big straight knife to cut through the cream and bottom layer.
Additional Recipes to try:
- Dirty Chai Tiramisu Cake
- Chocolate Tiramisu Ice Cream Cake
- Brown Butter Cake with Chocolate Cream Cheese Frosting
Ingredients
- All Purpose Flour: I’ve never tested choux pastry with anything other than all purpose so I recommend sticking with it.
- Butter: I like to use salted butter for all of the elements but unsalted will work too.
- Fine Sea Salt: Salt is key to balancing sweetness and enhancing the flavor of all of the elements.
- Egg: Three large eggs are used for the choux and then 6 egg yolks are needed for the vanilla bean pastry cream.
- Sugar: white granulated sugar is used for the pastry cream and dark brown sugar is used for the pecan pie filling.
- Starch: I like to use corn starch for the pastry cream but I believe arrowroot starch would work as well.
- Milk: Whole milk is used for the pastry cream and a little splash is in the pecan pie filling.
- Heavy cream: heavy cream is used for the pastry cream as well as the chocolate ganache.
- Vanilla extract: Vanilla extract is added into the pecan pie filling and vanilla bean paste is used in the vanilla pastry cream but you could definitely use vanilla bean paste for everything.
- Maple Syrup: Maple syrup is used in conjunction with the brown sugar for the pecan pie filling, make sure you’re using real maple syrup.
- Pecans: I love pecans in the fall but you could totally switch them for a different nut!
- Chocolate: I like to use 60% chocolate for the ganache but anything from 55%-75% should work!
How to make a Boston Cream Pie Karpatka
Choux Pastry
- Preheat the oven to 425 F and place a rack in the middle of the oven.
- Measure out the flour in a small bowl and set aside.
- In a medium sauce pot, add in the butter, water and salt.
- Heat over medium heat until just simmering. Briefly stir so that the water and butter are combined.
- Turn the heat to low and immediately dump all of the flour in at once.
- Use a wooden spoon to stir the dough together for about a 60 seconds. Once the dough starts to form a smooth ball, start stirring and mashing it more forcefully.
- Once cooked, place the dough into the bowl of a stand mixer and set it aside.
- Crack the eggs into a bowl or cup, ideally one with a spout for easier pouring and scramble with a fork until smooth.
- Use the paddle attachment on the mixer to beat the cooked dough for 3-4 minutes on medium low speed. This will help cool the dough before adding the eggs in.
- Leave the mixer running and gently pour 1/3 of the egg mixture in.
- Increase the speed of the mixer to medium and mix until the egg has been fully combined into the dough.
- Stop the mixer and scrape down the sides of the bowl. Then repeat the process of adding egg and mixing but you may not use all of the egg! The best way to know is to stop mixing and pull the paddle out of the batter slowly -it will stretch briefly and then break off in a V-shape. If it breaks immediately and makes a jagged edge, you need more egg.
Bake the Choux
- Line two 8″ metal round cake pans with parchment and then divide the dough evenly between the two.
- Use an offset spatula, dipping it in water as needed to prevent sticking, to spread the dough into even layers in each cake pan.
- Bake the choux in the hot oven for 20 minutes, then with the oven CLOSED, turn the heat down to 400 F and bake for another 15 minutes.
- Once golden brown and puffy, take the pans out of the oven and leave them and the choux to cool completely.
Make the pastry cream
- In a large pot, whisk together the corn starch and sugar. *If you need to do this in two batches you can! Then pour in the milk and 150 grams of the heavy cream and whisk to combine. Add in the egg yolks and salt and whisk once more.
- Place the pot over medium low heat and whisk constantly scraping the bottom and edges of the pot. It will feel like it’s taking a while but all of a sudden it’ll get really thick so don’t stop whisking. *It will get really thick, don’t stress.
- Once thick, remove the pot from the heat and whisk in the butter and vanilla bean paste until smooth.
- Pour the cream through a fine mesh sieve into a large shallow bowl or on a quarter sized baking sheet. Cover the surface with a layer of plastic wrap to prevent a skin from forming.
- Once cooled to room temperature, transfer the cream to the fridge and let it chill completely – this one needs to be fridge cold!
Pecan Pie Filling
- In a small pot add in the brown sugar, maple syrup, butter, milk, and salt. Heat over medium low heat until melted, stir and cook until combined and just bubbling.
- Turn off the heat and pour in the vanilla.
- Finely chop up the pecans – we’re not going for flour but they shouldn’t be huge chunks. Ideally 1/4″ or smaller.
- Add the chopped pecans into the pot and stir to combine. Transfer the mixture to a small bowl and place it in the fridge to cool and thicken.
- This doesn’t need to be cold before using just somewhat syrupy and thick and should no longer be hot.
Assemble
- Transfer the chilled pastry cream to a large mixing bowl and use an electric mixer to whip until smooth.
- Then add in the remaining 150 grams of cold heavy cream and whip until smooth and fluffy.
- You can either assemble this in an 8″ springform pan or with this metal cake collar. I did it with the metal cake collar on a large flat plate.
- Place one layer of the choux, flat side down, onto a large flat plate or small tray that will fit in the fridge. Tighten the cake collar around the choux.
- Scoop half of the pastry cream over the base layer of choux and spread it into an even layer. Spoon the cooled pecan pie filling over the pastry cream into an even layer all the way to the edges.
- Scoop the remaining half of the pastry cream over the filling and again smooth it into an even layer.
- Place the second layer of choux, again with the flat side down, onto the pastry cream and press down to squeeze out any air.
- Drape a piece of plastic over the top and set it in the fridge for 6 hours or overnight to set.
Chocolate Ganache
- Add the chopped chocolate into a medium heat safe bowl. Heat the heavy cream in a pot or the microwave until just steaming hot, not boiling.
- Pour the hot cream over the chocolate, cover with a lid and let it sit for 1 minute. After a minute has passed, remove the lid and whisk slowly until smooth.
- Take the chilled and set cake out of the fridge. Remove the plastic wrap and release and remove the cake collar. Transfer the cake to whichever dish you plan to serve it from.
- Pour the chocolate ganache all over the top of the cake. I like to let it run down the edges as well but it’s up to you! If needed use the back of a spoon to spread it out over the surface.
- Place the cake back in the fridge for 10 minutes to let the ganache firm up just a little – we don’t want it to be hard just not so runny.
- To serve, use a long serrated knife parallel to the top of the cake just to cut through the first layer of choux. Then switch to a big straight knife to cut through the cream and bottom layer. Store leftovers in the fridge for a day or two.
Boston Cream Pie Karpatka
Two layers of choux, filled with vanilla bean pastry cream, a layer of maple brown sugar pecans, and topped with chocolate ganache, this Boston Cream Pie Karpatka is my dream October birthday cake!
Servings: 12
Equipment
Ingredients
Choux Pastry
- 187 grams water
- 56 grams salted butter
- 1/4 teaspoon fine sea salt
- 130 grams all purpose flour
- 3 eggs large
Vanilla Pastry Cream
- 160 grams granulated sugar
- 75 grams corn starch
- 1/4 teaspoon fine sea salt
- 600 grams whole milk
- 300 grams heavy cream cold, *divided
- 6 egg yolks large eggs
- 1 teaspoon vanilla bean paste vanilla extract will work too
Pecan Pie Filling
- 40 grams salted butter
- 45 grams dark brown sugar
- 1/4 teaspoon fine sea salt
- 20 grams maple syrup
- 20 grams whole milk
- 1 teaspoon vanilla extract
- 100 grams pecans
Chocolate Ganache
- 175 grams 60% chocolate
- 190 grams heavy cream
Instructions
Choux Pastry
- Preheat the oven to 425 F and place a rack in the middle of the oven.
- Measure out the flour in a small bowl and set aside.
- In a medium sauce pot, add in the butter, water and salt.
- Heat over medium heat until just simmering. Briefly stir so that the water and butter are combined.
- Turn the heat to low and immediately dump all of the flour in at once.
- Use a wooden spoon to stir the dough together for about a 60 seconds. Once the dough starts to form a smooth ball, start stirring and mashing it more forcefully.
- Once cooked, place the dough into the bowl of a stand mixer and set it aside.
- Crack the eggs into a bowl or cup, ideally one with a spout for easier pouring and scramble with a fork until smooth.
- Use the paddle attachment on the mixer to beat the cooked dough for 3-4 minutes on medium low speed. This will help cool the dough before adding the eggs in.
- Leave the mixer running and gently pour 1/3 of the egg mixture in.
- Increase the speed of the mixer to medium and mix until the egg has been fully combined into the dough.
- Stop the mixer and scrape down the sides of the bowl. Then repeat the process of adding egg and mixing but you may not use all of the egg! The best way to know is to stop mixing and pull the paddle out of the batter slowly -it will stretch briefly and then break off in a V-shape. If it breaks immediately and makes a jagged edge, you need more egg.
Bake the Choux
- Line two 8″ metal round cake pans with parchment and then divide the dough evenly between the two.
- Use an offset spatula, dipping it in water as needed to prevent sticking, to spread the dough into even layers in each cake pan.
- Bake the choux in the hot oven for 20 minutes, then with the oven CLOSED, turn the heat down to 400 F and bake for another 15 minutes.
- Once golden brown and puffy, take the pans out of the oven and leave them and the choux to cool completely.
Make the pastry cream
- In a large pot, whisk together the corn starch and sugar. *If you need to do this in two batches you can! Then pour in the milk and 150 grams of the heavy cream and whisk to combine. Add in the egg yolks and salt and whisk once more.
- Place the pot over medium low heat and whisk constantly scraping the bottom and edges of the pot. It will feel like it’s taking a while but all of a sudden it’ll get really thick so don’t stop whisking. *It will get really thick, don’t stress.
- Once thick, remove the pot from the heat and whisk in the butter and vanilla bean paste until smooth.
- Pour the cream through a fine mesh sieve into a large shallow bowl or on a quarter sized baking sheet. Cover the surface with a layer of plastic wrap to prevent a skin from forming.
- Once cooled to room temperature, transfer the cream to the fridge and let it chill completely – this one needs to be fridge cold!
Pecan Pie Filling
- In a small pot add in the brown sugar, maple syrup, butter, milk, and salt. Heat over medium low heat until melted, stir and cook until combined and just bubbling.
- Turn off the heat and pour in the vanilla.
- Finely chop up the pecans – we’re not going for flour but they shouldn’t be huge chunks. Ideally 1/4″ or smaller.
- Add the chopped pecans into the pot and stir to combine. Transfer the mixture to a small bowl and place it in the fridge to cool and thicken.
- This doesn’t need to be cold before using just somewhat syrupy and thick and should no longer be hot.
Assemble
- Transfer the chilled pastry cream to a large mixing bowl and use an electric mixer to whip until smooth.
- Then add in the remaining 150 grams of cold heavy cream and whip until smooth and fluffy.
- You can either assemble this in an 8″ springform pan or with this metal cake collar. I did it with the metal cake collar on a large flat plate.
- Place one layer of the choux, flat side down, onto a large flat plate or small tray that will fit in the fridge. Tighten the cake collar around the choux.
- Scoop half of the pastry cream over the base layer of choux and spread it into an even layer. Spoon the cooled pecan pie filling over the pastry cream into an even layer all the way to the edges.
- Scoop the remaining half of the pastry cream over the filling and again smooth it into an even layer.
- Place the second layer of choux, again with the flat side down, onto the pastry cream and press down to squeeze out any air.
- Drape a piece of plastic over the top and set it in the fridge for 6 hours or overnight to set.
Chocolate Ganache
- Add the chopped chocolate into a medium heat safe bowl. Heat the heavy cream in a pot or the microwave until just steaming hot, not boiling.
- Pour the hot cream over the chocolate, cover with a lid and let it sit for 1 minute. After a minute has passed, remove the lid and whisk slowly until smooth.
- Take the chilled and set cake out of the fridge. Remove the plastic wrap and release and remove the cake collar. Transfer the cake to whichever dish you plan to serve it from.
- Pour the chocolate ganache all over the top of the cake. I like to let it run down the edges as well but it’s up to you! If needed use the back of a spoon to spread it out over the surface.
- Place the cake back in the fridge for 10 minutes to let the ganache firm up just a little – we don’t want it to be hard just not so runny.
- To serve, use a long serrated knife parallel to the top of the cake just to cut through the first layer of choux. Then switch to a big straight knife to cut through the cream and bottom layer. Store leftovers in the fridge for a day or two.
Notes
Tips for making a Boston Cream Pie Karpatka
- Once you add the flour to the hot butter, water, and salt – stir immediately and forcefully. You need to work the flour into the liquids and cook the raw flour.
- When adding the eggs I recommend first whisking them in a container with a spout – this will make it easier to add the right amount of egg because you won’t always need all of the eggs.
- During the baking process, do not open the oven! You need the steam in the oven to help the choux pastry puff!
- When making the pastry cream, don’t walk away from it – it’s important to keep whisking to prevent the eggs from curdling and keep the starch from clumping.
- It will start to thicken and at first look a little lumpy but it will smooth out as it continues to thicken.
- I love the pecan pie filling layer but if you can’t have nuts or just don’t want it you can absolutely leave it out or swap it with a jam!
- This cake can be a little tricky to cut. I’ve found that the best system is to use a long serrated knife parallel to the top of the cake just to cut through the first layer of choux. Then switch to a big straight knife to cut through the cream and bottom layer.
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