Chop 75 g chocolate and melt over a warm water bath. Cream 60 g butter, 75 g sugar and vanilla sugar with the whisk of the hand mixer. Stir in chopped chocolate and egg.
Mix flour, baking powder and cocoa, knead into the egg mixture with the dough hooks of the hand mixer.
Form the dough into approx. 12 balls of the same size and place them on a baking tray lined with baking paper. Press a depression in the middle of each ball. Bake in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see
manufacturer) bake for about 12 minutes. After about half the baking time, strengthen the hollows with a spoon. When baking is finished, remove from the oven and allow to cool on a cake rack.
In the meantime, bring 100 g sugar, 35 g butter and 125 g cream to the boil in a saucepan. Let simmer for about 5 minutes, stirring constantly. Pour into a bowl and let it cool down for about 30 minutes.
Chop 100 g chocolate, bring 50 g cream to the boil, remove from the heat. Melt the chocolate in the cream while stirring. Pour into a bowl and let it cool down for about 30 minutes.
Fill the biscuits half each with chocolate and caramel. Chill for about 30 minutes.