Preheat your oven to 350°F (175°C). Prepare two 9-inch round cake pans by greasing and lining with parchment paper.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, dark cocoa powder, baking powder, baking soda, and salt.

In a separate bowl, beat together the eggs, vegetable oil, vanilla extract, and buttermilk until well combined.

Pour the wet mixture into the dry ingredients and stir gently until just combined. Divide the batter evenly between the prepared pans.

Bake in the preheated oven for 25-30 minutes. Let cool in pans for 10 minutes before transferring to a wire rack to cool completely.

In a saucepan, combine cherry juice, cornstarch, and water. Heat over medium heat until thickened, then stir in drained morello cherries and Kirsch. Let cool.

Chill a mixing bowl and beaters in the freezer for 15 minutes. Pour heavy cream, powdered sugar, and vanilla extract into the bowl. Beat until stiff peaks form.

Slice each cooled cake layer horizontally to create four layers. Spread whipped cream on the first layer, add a third of the cherry filling, and repeat with the remaining layers.

Frost the top and sides of the cake with remaining whipped cream. Garnish with chocolate shavings and fresh cherries if desired.

Chill the cake in the refrigerator for at least two hours before serving.