3/4cup(75g) Dutch-process cocoa powderspooned and leveled
9large eggsseparated and room temperature
3/4cup(150g) granulated sugar
1/2cup(120mL) canola oil
Ganache
1cup(240ml) heavy cream
2cup(340g) dark chocolate
Instructions
Vanilla Diplomat Cream
Begin with beating the egg yolks and the sugar a few minutes, until it turns pale yellow. Place the mixture over a double boiler and add the butter, whisking continuously until it thickens. It might look like it is separating at one point- just keep whisking. Once it comes back together, let it thicken similar to the consistency of ranch- still runny but it feels thick and creamy.
4 large egg yolks, 1/4 cup (50g) granulated sugar, 1/2 cup (113g) butter
Allow it to cool completely (leave it out a few hours and do not refrigerate before adding the cool whip- it will look even thicker at this point). After it has cooled, add in the cool whip and vanilla. Beat until fully combined and refrigerate it until it is time to assemble the cake (don't leave out at room temperature for more than a few hours).
8 oz (227g) cool whip, 1 Tbsp vanilla
Chocolate Sponge Cake
Preheat the oven to 425F (218C) convection (400F/204C conventional) and combine the flour and cocoa powder and set aside.
1 cup (120g) all-purpose flour, 3/4 cup (75g) Dutch-process cocoa powder
On medium speed, begin beating the egg whites and slowly add in the sugar, like the start of a meringue. Beat until it is about doubled. Add in the egg yolks and beat until fully combined. Then add in the oil and beat until fully combined.
9 large eggs, 3/4 cup (150g) granulated sugar, 1/2 cup (120mL) canola oil
Lower the speed to low-medium and slowly add in the flour mixture. Mix just until it is combined.
Grease the bottom side of an 8" cake pan and use just enough batter to cover the surface of the pan. Make sure to go all the way to the edge but not past it. Bake for about 4-7 minutes. Remove from the oven and use a knife to release the cake from the pan.
Assemble
Once a few layers are baked and cooled, you can begin assembling the cake. Place a layer of the cake on a cake stand and top with a layer of the buttercream that is about the same thickness as the cake layers . Repeat until all layers of cake and buttercream are used (I had 15 layers).
Ganache
Heat the heavy cream in a sauce pan and just before boiling, remove it and pour over the chocolate. Let it sit for a minute and then stir until it is silky smooth. Pour over the cake and allow it to set in the fridge before serving.
1 cup (240ml) heavy cream, 2 cup (340g) dark chocolate
Notes
The runnier you leave the buttercream base, the runnier it will be when it is finished and it will make it more difficult to put together. You don’t want to over cook the buttercream base because it can burn. You will know it’s burned because it turns grainy.You can make an 8″ (or a shorter 9″) cake or two 6″ cakes with this batter. For the 6″, you will want to bake each layer for 4-5 minutes and for a larger cake, about 6-7 minutes.I put one pan in the oven and then two minutes later I put the other in, so it made an assembly line. By the time I finished removing one from the oven and putting the new one in, the second pan was ready to come out.