Separate eggs. Beat the egg whites until stiff, then add 70 g sugar. Beat the egg yolks, 100 g sugar and 5 tbsp lukewarm water until foamy. Sift 50 g starch, flour, cocoa and baking powder on top. Fold in with the beaten egg white. Spread the dough on a baking tray lined with baking paper (approx. 35 x 40 cm). Bake in a hot oven (electric cooker: 200 °C / convection oven: 175 °C / gas: level 3) for approx. 15 minutes
Heat the jam. Sprinkle tea towel with 2 tablespoons of sugar. Turn out the sponge cake and remove the baking paper. Drizzle with cherry brandy, spread with jam and roll up with the help of the cloth. Let it cool down
Collect the cherry juice, if necessary add water to 200 ml. Mix 8 tbsp. juice and 25 g starch. Boil up the rest of the juice and 2 tbsp. sugar. Stir in starch, bring to the boil briefly. Fold in cherries. Let cool down
Place the springform pan rim (26 cm Ø) on a cake plate. Cut the sponge roll into about 26 slices. Place approx. 14 slices on the edge of the cake tin and place the rest in the middle as a base. Whip cream, firming agent and 3 tbsp. sugar until stiff. Fold in sour cream and lemon juice. Fill half into the mould. Spread the compote on top. Spread the rest of the cream on top. Chill for 4-5 hours. Remove the edge of the mould. Decorate Charlotte with crumbled chocolate, cherries and mint