Roughly chop the chocolate. Beat the fat, sugar, 1 packet of vanillin sugar and salt with the whisk of the hand mixer until foamy. Add the eggs one by one and stir in. Mix flour, baking powder and nuts and stir in.
Fold in chocolate. Line the bottom of a springform pan (26 cm Ø) with baking paper, fill in the dough and smooth it down. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for 25-30 minutes.
Remove from the oven, remove the base from the edge of the springform pan with a sharp knife and let it cool down on a grid. Remove from the baking tin and remove the baking paper. Mix the remaining vanilla sugar and cream thickener.
Whip the cream in 2 portions until stiff, allowing the mixture to trickle in. Stir 6 tablespoons egg liqueur into the cream. Spread about 2/3 of the advocaat cream on the cake base. Spread half of the remaining advocaat cream on the edge of the cake.
Decorate with grated chocolate. Pour the remaining cream into a piping bag with a perforated spout and squirt it onto the edge of the cake as "eggs". Fill with remaining advocaat. Decorate the middle of the cake with sugar eggs as desired.
Results in about 12 pieces.