Melt the butter. Then stir well with the sugar until frothy. (The better you stir, the softer the dough will be later). Then gradually add the eggs and stir well. Stir in the flour along with the baking powder, add the vanilla sugar. Season the dough with cinnamon and stir.
Chop the chocolate and peel and grate the apples and fold everything into the batter. Fill into a greased muffin tin or into small paper cases and bake for about 25 - 35 minutes at 180 ° C in the preheated oven.
After baking, dust with powdered sugar and decorate with chocolate icing if you like (I only swirled the chocolate over it once to make it look nicer if the muffins weren`t completely covered with chocolate, they are sweet enough!).