• Preheat the oven to 350 F and place a rack in the middle of the oven.

Marble Cake Batter

• In a medium bowl, whisk together the softened butter, sugar, salt, almond extract and vanilla extract until smooth, light and fluffy. You really gotta whip it so feel free to use an electric mixer. The whole mixture should lighten in color!
• Whisk in the eggs, one at a time. Ensure each egg has been fully mixed in before adding the next.
• Pour in the hazelnut flour and whisk again.
• Lastly, pour in the flour and baking powder.
• Whisk once more until combined and smooth.
• Pour 350 grams of the batter into a second bowl.
• Sift the cocoa powder and espresso powder into the first bowl along with the milk and whisk until smooth.
• Spray the 7" metal springform cake pan (it needs to be at least 3" tall) with your baking spray and then alternate spoonfuls of vanilla and chocolate cake batter until both have been fully used up.
• Tap the cake on the counter until the top is level.

Bake the Cake

• Bake the cake in the preheated oven for 20 minutes. After 20 minutes, rotate the cake 180 degrees and bake for another 15-20 minutes.
• When the cake is finished baking, check it by sticking a toothpick into the center of the cake. If the toothpick comes out clean, the cake is fully baked.
• Remove the cake from the oven and leave it to cool for 10 minutes before removing the spring form.
• After 10 minutes, remove the springform.
• Allow the cake to cool completely before assembling.

Chocolate Hazelnut Ganache

• Roughly chop the chocolate and place in a heat safe bowl.
• Heat the cream in a sauce pot over medium heat until steaming.
• Pour the hot cream over the chocolate and leave it to sit for 2 minutes.
• Whisk the cream and chocolate together until fully combined. Set aside to cool, stirring regularly until thick.
• To speed this up place the bowl in an ice bath or on an ice pack. Just don't forget to keep stirring. You can also make this in advance and store it in the fridge but it will need to warm up before using it.
• Once thick, stir in the chocolate hazelnut spread if using.

Vanilla Mascarpone Whipped Cream

• In a medium mixing bowl, add in the cold mascarpone, sugar, vanilla bean insides, salt, and vanilla extract.
• Use the paddle attachment to cream the mascarpone mixture on medium speed for 3 minutes until the sugar has fully dissolved. If using a hand mixer, the regular beater attachments will work.
• Turn off the mixer and pour in the cold heavy cream.
• Switch to the whisk attachment and whip on medium speed until medium stiff peaks form. Do not over whip it, it's better to under whip rather than over whip. If you over whip it, pour in a little extra heavy cream and use a rubber spatula to fold it in.
• Cover and place in the fridge to firm up until ready to assemble.

Soak

• Brew one shot of espresso (1.5 ounces) and mix it with 1.5 ounces of milk.
• Set aside to cool.

Assemble

• Level off the domed top of the cake first with a serrated knife, then cut into 3 equal layer.
• Place the bottom layer on a piece of parchment paper and brush the surface with the coffee soak.
• Brush the top of the bottom and middle layers, and the bottom of the top layer, with the vanilla milk soak until it has all been used up.
• Scoop 1/2 a cup of the mascarpone frosting onto the bottom layer of cake and use the back of a spoon or rubber spatula to spread it out. Stop about 1/4" from the edge of the cake. Spread the cream so that the edges are thicker and the center is a thinner layer of cream.
• Put the ganache into a piping bag or ziploc bag and cut the tip off. Pipe half of the ganache over the whipped cream, staying within an inch of the edge of the cake.
• Carefully use an offset spatula to spread the ganache into an even layer without mixing in the cream. Sprinkle with 1/4 cup of the chopped hazelnuts.
• Layer the middle layer of cake over the fillings and press down gently.
• Repeat the soak, cream, ganache, and hazelnuts on the middle layer of cake.
• Place the top layer of cake over the fillings and press down gently.
• Soak the top layer with the remaining coffee. Spoon almost all of the remaining whipped cream over the top of the cake. Use an offset spatula to spread it over the top of the cake and then down over the sides.
• If you want a smooth cake, use a bench scraper to smooth out the sides and place the cake in the fridge overnight. I usually place a bowl over the cake upside down to keep it from drying out. But if you plan to add more cream, you can also wrap the cake with plastic wrap.
• Place the remaining whipped cream in a covered bowl in the fridge. The next day, decorate the firmed cake with the remaining cream and top with more chopped hazelnuts.