Begin by making the pastry cream for the Diplomat cream the night before or at least a few hours before frosting the cake, so it has time to cool.

In a small saucepan, over low heat, whisk together the eggs, granulated sugar, cocoa powder and butter. Allow them to melt and cook while whisking continuously for about 10 minutes. 

Once the custard gets the consistency of lemon curd, remove it from the heat and pour it into a separate bowl.

Cover the surface with plastic wrap and allow it to cool to room temperature. 

Remove the pit and chop the cherries into quarters. Place them in a medium saucepan over medium heat with the powdered sugar and lemon juice. Allow them to simmer until they soften. 

Remove 2 Tbsp of the juice from the pan and mix it in a small separate bowl with the cornstarch.

Add the cornstarch mixture to the cherries and allow everything to simmer over low-medium heat for a few minutes. 

Remove from the heat and stir in the bourbon or kirsch.

You can either leave the cherry sauce chunky, or you can use an emulsion blender to make it into a smooth sauce. Allow it to cool completely while baking the cake. 

To make the chocolate cake, preheat the oven to 3350/177C convection (or 325F/162C conventional) and grease and line the base of three 6-inch cake pans or two 8 inch cake pans. 

In a medium bowl, whisk together the flour, granulated sugar, cocoa powder, baking soda, espresso powder and salt. Set the dry ingredients aside.

In a large bowl, whisk together the eggs, oil, buttermilk, coffee and vanilla extract until they’re well combined.

Sift the dry ingredients over the wet ingredients and fold them together just until the last streak of flour is combined. 

Distribute the batter evenly among the prepared cake pans (about 16oz each for three 6-inch pan or 24oz each for two 8 inch pans).

Bake for 35-45 minutes, until the center of the cake springs back when it's poked or a toothpick inserted comes out clean. Remove the cakes from the pan and allow them to cool completely. 

Once the custard for the diplomat cream has cooled, use an electric mixer to beat it on medium-high speed with the cool whip and the vanilla, just until they're combined. 

Place the bottom layer of cake on flat surface. Top with ⅓ of the chocolate diplomat cream and a layer of cherry preserves. Repeat with the second layer. 

For the third layer, top with the rest of the chocolate cream and fresh, whole cherries. Place it in the refrigerator immediately so it can set for at least 30 minutes to an hour.