Preheat oven to 250 degrees. Slice chestnuts lightly with a sharp kitchen knife, place on baking sheet and place in oven for approx. 20 min (gas: 5) until skins crack. Take them out and remove the skin while they are still hot.
2. put chestnuts in a saucepan, pour 1/2 L milk and slit vanilla bean. Simmer until soft and light in about 45 minutes (the milk is almost absorbed). Remove vanilla bean, crush chestnuts.
Mix the powdered sugar, cocoa and rum into the puree and stir until smooth. Divide evenly among dessert bowls, whip the whipped cream until stiff and garnish the puree with it.
Note: You can make instead of milk in water (very lightly season with salt), instead of rum use cognac and just as omit the cocoa of your choice.