Beat the sugar with the three eggs until frothy, until the mixture is light. Mix in the flour. Carefully melt the butter together with the cooking chocolate in a saucepan and mix into the sugar-egg-flour mixture. Finally add kirsch to the mixture.
Bake for 11 minutes at 250 degrees on the second groove from the bottom in a preheated oven in a round springform pan (approx. 26 cm diameter, lined with baking paper). It is important to strictly adhere to the baking time! The inside of the cake should still be slightly moist. If necessary, reduce the baking time by 30-60 seconds.
The cake is very flat, but it has to be that way. It tastes best to me when it is allowed to cool properly in the refrigerator after baking.