For the Rainbow Muffins put butter, sugar and vanilla sugar in a bowl and mix well. Add the eggs and mix well again.
Add flour, baking powder and salt to another bowl. Add flour mixture and milk to egg-butter-sugar mixture and stir to divide the whole mixture among as many glass bowls as you have color.
Add the food coloring to taste. Grease/line the muffin tray, layer as desired in the molds and bake for 12-15 minutes at 180 °C.
Let cool, brush warmed powdered sugar (liquid) on top.
Preparation Tip:
If you like, add a few sprinkles on top of the Rainbow Muffins.