Coffee Oreo Cake Recipe

Method

Custard for the Diplomat Cream

Begin by making the custard portion for the diplomat cream so it has time to cool. Place the egg yolks, granulated sugar and butter in a small saucepan over low heat and whisk continuously for about 5 minutes.
6 large egg yolks room temperature, 1/2 cup (100g) granulated sugar, 1 cup (227g) unsalted butter softened
The mixture will look chunky before it melts. After it melts, continue cooking it until it thickens enough to coat the back of a spoon and resembles lemon curd. Quickly remove it from the heat, pour it into a heat safe container and cover it with a lid. Set it aside to cool completely to room temperature.

Vanilla Coffee Sponge Cake

Preheat the oven to 350F/177C convection (325F/163C conventional) and grease four 8-inch pans.
Place the egg whites in a large bowl and use an electric mixer to beat the egg whites at full speed until they're frothy and have reached the top of the bowl, add in the cup of sugar and beat until the meringue has stiff peaks.
12 large eggs room temperature and separated, 1 cup (200g) granulated sugar
Pour in the egg yolks and mix just until they're fully combined. With the mixer on low-medium speed, add in the flour and baking soda, 1-2 Tbsp at a time. Mix just until the flour is incorporated.
2 cups (240g) all-purpose flour spooned and leveled, 1/4 tsp baking soda
Distribute the batter evenly among the four pans and bake for about 17 minutes, until the cake is golden and separates itself from the edge of the pan. It will also spring back when you press on it gently. Flip the cakes over onto a tea towel and allow them to cool completely.
Meanwhile, dissolve the 1/4 cup of granulated sugar in the coffee and allow it to cool while the cakes bake.
1/4 cup (50g) granulated sugar, 4 cups (24oz) brewed coffee or cold brew chilled

Finish Diplomat Cream

At this point, dissolve the gelatin in water and the espresso powder in water and set aside.
2 tsp gelatin dissolved in 2 tsp water, 2 tsp espresso powder or 2 Tbsp instant coffee dissolved in equal amounts of water
Use an electric mixer with a large bowl to beat together the heavy whipping cream with the powdered sugar until stiff peaks form. Add in the cooled custard mixture, the dissolved coffee and the dissolved gelatin and beat the cream at medium speed, just until it is fully combined, don't over-mix.
2 1/2 cups (20oz) heavy whipping cream, 1/2 cup (60g) powdered sugar spooned and leveled
Fold in the Oreo chunks.
12 Oreos roughly chopped

Assemble

If the cake layers are a little uneven, use the largest one on the bottom and ALWAYS flip them upside down. The part of the cake that was on the bottom of the pan should always be facing upright when they're stacked.
Use 1 cup of the coffee to soak the first layer of cake (you can use a squeeze bottle, a sippy cup or just a spoon). Pour it slowly, a little at a time, letting it soak in and then do the rest. Make sure to use a full cup of coffee per layer of cake.
Use about 1/4 of the cream and spread it evenly on top of the first layer. Place the next layer on top and soak it with the coffee. Repeat this step until all the layers are used.
Refrigerate the cake for at least 2 hours before using the rest of the diplomat cream to frost the outside of the cake. DO NOT refrigerate the diplomat cream separately because the gelatin will set.
When the cake is finished, refrigerate it for at least another 2 hours before slicing and serving. Coffee Oreo Sponge Cake is best served cold or slightly chilled.

Notes

If you only have two 8″ pans, the batter will be ok to sit and wait for the first two to bake for 20 minutes.

To do a light coat of cream on the outside of the cake without Oreos make sure to set some cream aside before adding the Oreos.

To decorate this cake fancy on the outside, I suggest using an alternate buttercream for decorating. For example, American buttercream or a European buttercream- American Buttercream is the simplest but a European buttercream would compliment the flavors better. Don’t try anything fancy with this buttercream because it’s very light and fluffy, like whipped cream, so it won’t hold up.

This is a sponge cake so it’s very soft compared to a typical butter/oil cake, so make sure not to skip refrigeration time. I do not suggest doing more than four layers.