• Preheat the oven to 350℉ (180℃) and line the bottom of an 8-inch springform pan with parchment paper. Do NOT grease the sides of the pan.
• In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites with ½ cup sugar on high speed until soft peaks form, about 8 minutes. Transfer to a large bowl and set aside.
  5 large eggs, 1 cup granulated sugar
• In the bowl of the stand mixer fitted with the paddle attachment, combine egg yolks, the remaining ½ cup of sugar, and vanilla extract. Beat at medium speed until thick, creamy, and pale, about 3-5 minutes. Carefully fold the egg yolk mixture into the egg white mixture.
  1 teaspoon vanilla extract
• Combine all-purpose flour, baking powder, cornstarch, and cocoa powder. Working in batches, sieve the flour mixture over the egg mixture and fold in carefully until combined.
  1 cup all-purpose flour, 2 teaspoons baking powder, ⅓ cup cornstarch, ¼ cup unsweetened Dutch process cocoa powder
• Transfer to the springform pan and smooth the top with a spatula. Bake for 25 minutes, or until a skewer inserted in the center comes out clean with only a few crumbs attached.
• Remove the ring of the springform pan and carefully invert the cake onto a parchment paper-lined cooling rack, peel off the parchment paper from the bottom, and let it cool completely.
• When the cake has cooled completely, use a long serrated knife to cut the cake into three even layers.
• To make the cherry filling, we need the liquid from the jar of cherries. Set aside the cherries. Remove 4 Tbsp from the liquid and combine it in a small bowl with the cornstarch and sugar. Bring the remaining cherry juice in a small saucepan to a simmer, then remove it from the heat and whisk in the cornstarch mixture. Bring back to a simmer while whisking constantly until it starts to thicken. Stir in the cherries, simmer for 1-2 minutes until thick, then remove from heat. Add half of the kirsch to the cherries if you're using it. Let cool for 5-10 minutes.
  24 oz jar of morello cherries, 5 tablespoons cornstarch, 2 tablespoons sugar, ⅓ cup kirsch
• To make the whipped cream, beat 4 cups of heavy cream (depending on your mixer, you might have to whip the cream in two batches) in the bowl of a stand mixer fitted with the whisk attachment at high speed until soft peaks form. Then add powdered sugar and beat until stiff peaks form, about 2-3 minutes longer. The whipped cream should be very stiff and spreadable, but be careful not to overwhip it. Refrigerate whipped cream until ready to assemble the cake. Set aside about ¾ cup of whipped cream for decorating the cake.
  4 cups heavy cream, ½ cup powdered sugar

Assembling the cake

• Use the top layer of the cake as the bottom. On a serving platter, put a cake ring around the cake and two pieces of parchment paper below the cake (see notes above). Drizzle 1.5 tablespoons of kirsch (or cherry juice) over the cake layer, then top with half of the cherry mixture, leaving a 1-inch border. Top with about ¼ of the whipped cream, smoothing it out with a spatula.
• Top with the middle cake layer and repeat drizzling with liquid, topping with cherries and cream. Put the third cake layer on top (smooth side up). Spread ⅓ of the remaining whipped cream on top, then remove the cake ring and spread the remaining cream with a spatula around the sides of the cake until completely covered in whipped cream.
• Decorate the sides of the cake with grated chocolate. Pipe 16 swirls of whipped cream on top using the set-aside whipped cream, and garnish the middle of the cake with the remaining chocolate. Put a fresh cherry on each cream swirl and refrigerate the cake until serving.
  16 fresh cherries, 4 oz bittersweet Baking chocolate