Best Frosting Ever (And I Don't Even Like Frosting)

Here's my mother's Mocha Cake recipe. When she started to go downhill with lung cancer, I made her this cake for her birthday which she enjoyed.

Mocha Cake Recipe

Ingredients
1 Sunshine orange sponge cake
1 cup half and half
2 teaspoons powdered coffee
Whipped cream
Chopped walnuts
Butter mocha frosting

Bake or buy a sunshine sponge cake
Slice in 4 layers. Pour over them with a teaspoon, a cup half and half to which 1 teaspoon vanilla and 2 teaspoons powdered coffee dissolved in a very little water have been added. Fill with whipped cream and chopped walnuts. Frost with butter mocha frosting and decorate with whole walnuts.

Butter mocha frosting
½ lb. sweet butter
6 egg yolks
1 ¼ c. powdered sugar
4-5 level teaspoons powdered coffee, dissolved in water (least amount)
1 Tbsp. vanilla

Beat butter first, then add 1/8 cup of the sugar, then the egg yolks one at a time. Add ½ cup more sugar, then the coffee and vanilla, then the rest of the sugar. Refrigerate frosted cake for about 3 hours.