Place the baking mix, fat, egg, cocoa and 2 tablespoons of water in a mixing bowl. Stir with the whisk of the hand mixer. Fill the dough into a greased springform pan (26 cm Ø) and smooth it down.
With a teaspoon, place 100 g cranberries as small heaps on the dough. Bake in the preheated oven (electric cooker: 175 °C/ gas: level 2) for about 20 minutes. Let it cool down. Soak the gelatine in plenty of cold water.
Puree 200 g cranberries with a blender. Mix yoghurt, sugar, lemon peel and pureed cranberries with a whisk. Squeeze the gelatine and dissolve. Stir into the yoghurt mixture and chill.
In the meantime, whip 1 cup of cream until stiff. As soon as the yoghurt mass begins to set, fold in the cream with a whisk. Place the springform pan around the cake base and spread the yoghurt mixture on the cake base.
Chill for about 1 hour. Whip the rest of the cream until stiff and fill into a piping bag with star-shaped spout. Decorate cake with cream, remaining cranberries and chocolate shavings. Makes about 12 pieces.