Roast the walnuts in a pan without fat. Remove, let cool and put 24 halves aside. Finely chop the remaining nuts. Cut the vanilla pod lengthwise and scrape out the pulp with the back of a knife.
Cream fat, salt, vanilla pulp and sugar with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour and baking powder and stir in alternately with the milk.
24 Line the recesses of a mini muffin tray with baking cups. Spread the dough on the trays and bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 15-20 minutes.
Remove and let it cool down on a cake rack.
Roughly chop the chocolate and melt it in a bowl over a warm water bath. Drizzle some chocolate over the muffins and decorate each muffin with a half walnut kernel. Chill the muffins for about 20 minutes.