Mix butter in a bowl until soft
Mix in the sugar, vanilla sugar and salt
Mix in one egg after the other until the batter is very light in color
Add kirsch or rum
Mix the flour, hazelnuts and baking powder into the batter
Add currants and mix into the batter
Grease the silicone form with butter. Fill the silicone forms up to 3/4 with the batter
Place the silicone form in the preheated grill and let the muffins bake for approx. 20 minutes at 200° C.
Towards the end of the baking time, simply insert a wooden skewer or toothpick into the muffins and pull out again: If some batter sticks, then continue baking.