Melt the butter first. While the melted butter is cooling, chop the chocolate into small pieces and set aside. Beat the eggs and beat them with the sugar in a bowl until frothy.
Preheat the oven to 200 ° C.
Mix the flour, baking powder, salt and the grated lemon zest in a separate bowl and add to the egg mixture. Add the orange flavor. Stir in the cooled butter and add the chocolate chips. Mix the dough again.
Put the dough in a greased muffin tin and bake the muffins at 200 ° C for about 15-20 minutes. Once the muffins have cooled, they will be easier to remove from the mold. Cover the muffins with a chocolate icing and decorate if necessary.