Separate eggs while cold, then let whites come to room temperature for 20 minutes. Beat egg whites on medium-high speed for 3-4 minutes until stiff, glossy peaks form.
4 large eggs
Whisk melted butter, egg yolks, sugar, flour, cocoa powder, and baking powder until smooth. Fold in one-third of the egg whites gently with 10 strokes using a spatula, then fold in the remaining whites just until no streaks remain.
2 tbsp cocoa powder, 1 cup all-purpose flour, 0.75 cup sugar, 4 large eggs, 1 tsp baking powder, 0.25 cup butter
Pour batter into greased 8-9 inch springform pan. Bake at 350°F for 25-30 minutes until top springs back and a toothpick comes out clean. Cool in pan 10 minutes, then turn out onto a rack to cool completely.
Chill mixing bowl and whisk for 20 minutes. Beat cold whipping cream with powdered sugar on medium-high until soft peaks form, about 2-3 minutes. Drain sour cherries on paper towels for 15 minutes.
2 cups whipping cream, 0.25 cup powdered sugar, 24 oz sour Morello cherries
Slice cooled sponge horizontally into 2-3 even layers. Brush each layer lightly with 1-2 tablespoon Kirsch. Spread whipped cream on the first layer, add drained cherries, then repeat with remaining layers. Frost sides and top with remaining cream, pressing chocolate shavings on sides. Chill for 2 hours before slicing.
2 cups whipping cream, 24 oz sour Morello cherries, 3 tbsp Kirsch
