Solar cake in a coffee mug - single (or double) serving

Coffee Mug Cake

(RECIPE AT BOTTOM)

Add a tablespoon of butter.
2 tablespoons of sugar and mix until it’s fluffy and creamy, maybe 30 seconds
1/2 egg
2 tablespoons of sour cream
few drops of vanilla
1/4 cup of flour

1/8 teaspoon baking powder

Not browned but yummy! Needed frosting like any other cake. Now who would eat cake without frosting?  For frosting mix butter (or Crisco) and powdered sugar, drop of vanilla if available.