A soft and fluffy yogurt cake batter filled with berries, topped with plums, more berries, a buttery streusel and a lemon glaze, this Plum Berry Crumb Cake is perfect for summer.

Side view of a slice of Plum Berry Crumb Cake topped with lemon glaze on a white plate.

What is a Crumb Cake?

A crumb cake is also known as a streuselkuchen in Europe and it’s generally a simple cake topped with a thick buttery crumb topping. The crumb topping is usually made from flour, butter, sugar, salt, and vanilla.

Can I swap out the fruit?

Yes! Just make sure your fruits aren’t too juicy. For the berries I would stick with raspberries or blueberries or both. For the plums, you could swap them for peaches or apricots!

Can I make this crumb cake in advance?

Yes! This cake is delicious warm from the oven (it does need to cool a bit first to hold together) but you can also make it the day before, let it come to room temp and cover the top with a sheet of plastic wrap. If you want to make it a few days in advance, wait to glaze it and transfer it to an airtight container and store it in the fridge; just be sure to let it warm up or come to room temperature before serving it.

Tips for making a Plum Berry Crumb Cake

Any type of plums will work but you could also swap them out for peaches or apricots.
Fresh or frozen berries can be used for the batter and topping! If they’re frozen don’t defrost them first.
Make sure all the ingredients are at room temperature – this will help get a smooth and fluffy cake batter.
I recommend using this 9″x9″ square pan from USA pan because it’s non-stick, and the sides are nice and tall. If you want to be able to lift the whole cake out, I recommend adding in a rectangle of brown parchment paper that reaches from one side to the other to use as a sort of sling.
This cake can be difficult to tell when it is finished baking, but you’ll know it’s done when the streusel is golden brown and there isn’t MUCH of a wobble left on the cake. It’s ok if it still wobbles a little bit though.
Let the cake cool for at least 10-15 minutes before glazing and then another 15 minutes before slicing and serving.

Additional Crumb Cakes to try!

Ingredients for Plum Berry Crumb Cake

Lemons: Lemon zest is used in the cake batter and lemon juice is used for the glaze.
Sugar: White granulated sugar is used in the crumb and cake batter and powdered sugar is used for the glaze
Vanilla Extract: Vanilla adds flavor and enhances the sweetness of all of the elements.
Salt: Fine sea salt helps balance out all of the sweetness in the cake and enhances the flavors.
All Purpose Flour: Any all purpose flour will work for this cake, I use King Arthur all-purpose flour! The flour is used in both the cake batter and the crumb.
Butter: Butter adds moisture and richness to this cake and to the crumb layer. I use salted butter but you could use unsalted too for this cake.
Baking Soda & Baking Powder: These both help make the cake rise – make sure to check the expiration date! If they are expired, they won’t be very effective.
Eggs: I use standard large eggs from the store, make sure they are at room temperature.
Yogurt: Full fat greek yogurt keeps this cake tender and soft!
Plums: I used standard black plums but red plums would work too!
Berries: I used half raspberries and half blueberries but you could do 100% of either as well.

Side view of a slice of Plum Berry Crumb cake on a shallow white bowl in the sun.

How to make a Plum Berry Crumb Cake?

Make the Streusel

In a medium bowl add in the soft butter, sugar, salt and vanilla. Use a fork to stir together until smooth.
Pour in the flour and use the fork to rub the flour into the butter mixture until fully combined.

Cake Batter

Preheat the oven to 350 F and place a rack in the center.
In a medium bowl add in the sugar and lemon zest. Rub the zest into the sugar with your fingers until fragrant. Then add in the flour, baking soda, baking powder, and salt and whisk to combine.
Add in the soft butter, yogurt, eggs, and vanilla.
Use the paddle attachment or an electric hand mixer to mix the ingredients first on medium low until 90% combined.
Pour in 150 grams of raspberries and 100 grams of blueberries into the cake batter. Use a flat rubber spatula to fold them in and finish mixing the batter.
Line the pan with a rectangle of parchment that is 15″ x 8″ from one side to another. Pour in the cake batter.
Smooth out the cake with a rubber spatula or a mini offset spatula.

Assemble and Bake the Cake

Cut the plums in half and remove the pits. Then cut each half into four slices and then each of those in half again (if you can) to have 8 slices (per half of plum).
Lay the slices down on their sides in rows across the top of the cake to cover the surface. Top with the remaining berries.
Clump the streusel and sprinkle it over the fruit layer.
Place the cake into the preheated oven and bake for 30 minutes. Rotate the cake 180 degrees and bake for 30-35 more minutes.
The cake will be done when the streusel will be slightly more golden brown on the edges. and the cake should only have a very slight or no wobble.
Once baked, remove from the oven and make the glaze while it starts to cool.

Lemon Glaze

In a medium bowl add in the powdered sugar and lemon juice.
Whisk to combine until smooth. If it’s too thin add more powdered sugar, if it’s too thick add a bit more lemon juice.
While the cake is still warm, pour the glaze on top and use the back of a spoon to spread it over the streusel.
Leave the cake to cool for at least 20 minutes on a wire rack. Ideally you want the glaze to set until the glaze is hard and crackly. Think glazed donut.
Run a knife along the edge between the cake and the pan. Then either lift the cake out with the parchment or slice the cake while it’s still in the pan.

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