Set aside 24 beautiful walnut halves. Finely mix the remaining walnut kernels and biscuits in the universal chopper. Mix coffee and 2 tablespoons of hot water
Separate eggs. Stir egg yolks and 60 g sugar until light creamy. Add coffee, butter and nut biscuit mixture and mix to a smooth dough. Mix flour and baking powder and stir in. Beat the egg whites until stiff, adding 60 g of sugar. Fold the beaten egg whites into the dough
Pour the dough into 24 slightly moistened mini silicone pans. Place a nut kernel on each cake and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 20 minutes. Remove from the cake tins and let cool on a cake rack