How to make
Beat the butter, sugar, flour, eggs and vanilla. Oil 12 muffin cups and distribute the mixture.
Bake the muffins in a preheated 360°F (180 °C) oven for 18-20 min.
Melt all 3 types of chocolate in a water bath in separate bowls.
Put 1/3 of the butter in each type of chocolate.
Decorate 4 of the muffins with the white chocolate, 4 with the dark and the last 4 with the milk chocolate.