For the biscuits, melt butter and let it cool down a little. Finely chop the chocolate. Mix flour, baking powder, sugar, vanilla sugar, cocoa and 1 pinch of salt. Stir the eggs until creamy. Add butter slowly while stirring. First stir in the flour mixture, then the chopped chocolate.
Using a teaspoon, place approx. 44 heaps (approx. 4 cm Ø) at a sufficient distance on baking trays lined with baking paper. Bake one after the other in a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for about 10 minutes. Let the soft biscuits cool down first, then carefully place them on a cake rack and let them cool down.
For the filling, chop 300 g candies. Heat the cream and dissolve the sweets in it. Boil down for about 10 minutes while stirring. Let it cool down first, then put it in a cool place for about 2 hours.
Whip the toffee cream in 2 portions until creamy, pouring in 1 sachet of cream firming agent at a time. Finely chop 50 g candies and fold in. Pour the toffee cream into a piping bag with a large perforated spout and spray it spirally onto the smooth underside of 22 biscuits. Place the remaining biscuits on top as a lid and chill for at least 30 minutes.
Coarsely chop the chocolate coating, melt in a hot water bath and let it cool down a little. Coarsely chop the nuts. Dribble some chocolate coating onto each cookie and sprinkle with nuts. Keep cool until serving.