Melt the butter on low heat on a saucepan.
Chop the white chocolate and add to the melted hot butter. Mix well till all the chocolate dissolves into the butter.
In the bowl of a stand mixer or with a hand-held mixer, beat together the eggs and sugar until fluffy and pale, this takes about 5 minutes.
Grate the marzipan into the egg mixture and whisk until the mixture is fluffy and creamy.
Sift flour and baking powder into the mixture. Add the chocolate butter mixture to the batter and mix everything together gently.
Grease muffin cups and pour the batter into them till half full.
If desired, you can stick in half a strawberry into each muffin, with the cut surface facing up.
Bake for 20 minutes at 180 degree centigrade. Cool and dust them lightly with icing sugar.
You can decorate them with sprinkles or more chocolate if desired.