To make this cake, you will double the Genoise cake recipe, stirring 1/3 cup unsweetened Dutch-process cocoa powder into the flour and salt. Bake in two 9-inch round cake pans that are buttered, lined with parchment paper, and dusted with cocoa powder. To make simple syrup with kirsch, stir in 1/3 cup kirsch to simple syrup recipe.
Slice each cake in half horizontally. Place 1 cake layer on a cake stand. Brush top with 1/4 cup simple syrup. Spread with 2 cups whipped cream, leaving a 1/2-inch border. Remove cherries from filling syrup with a slotted spoon, and transfer to a medium bowl. Scatter 1 1/4 cups cherries evenly over whipped cream. Drizzle with 2 tablespoons filling syrup. Repeat 2 times. Place final cake layer, cut side down, on top, and spread with ganache. Serve immediately.