Preheat the oven to 350°F / 180°C. Grease three 8in / 20cm round cake pans and line them with parchment paper.
Beat 6 large eggs, at room temperature, with 1 teaspoon of vanilla extract and 1¼ cups of superfine sugar for 7 minutes, until tripled in volume.
Gently fold in ⅔ cup of all-purpose flour and ½ cup of Dutch-process cocoa powder, then 150g of melted and cooled unsalted butter.
Divide among the pans and bake for 25 minutes, until springy and a skewer comes out clean. Cool completely.
Drain 670g of pitted morello cherries in syrup, keeping the juice. Stir the juice with ½ cup of superfine sugar and 4 teaspoons of cornstarch over low heat until slightly thickened.
Off the heat, stir in ⅓ cup of kirsch. Pour the syrup over the cherries and let cool.
Whip 4 cups of heavy cream with ⅓ cup of icing sugar and 2 teaspoons of vanilla extract to stiff peaks, about 5 minutes.
Brush a cake layer with the cherry syrup, spread with a quarter of the cream, and scatter with half of the cherries. Repeat with the second layer, then add the third and brush it with syrup.
Cover the top and sides with the remaining cream. Press curls and shavings of 100g of dark chocolate on top and around the base, and finish with 12 fresh cherries.
