For the chocolate muffins with raffaello centers, beat butter, sugar and vanilla sugar until creamy. Gradually add the yolks and mix everything for about 4 minutes.
Melt the chocolate over a bain-marie, let cool and stir in. Mix flour, cornstarch and baking powder and stir into the batter.
Finally, beat the egg whites until stiff and gently fold in. Fill the muffin cups halfway with the mixture, then place a Raffaello in the center of each and fill with the batter.
Bake the chocolate muffins with Raffaello centers at 180 degrees in a preheated oven for about 25 minutes.