Frosting for German Chocolate Cake

1 cup half-and-half

½ cup butter

1 cup white sugar

3 egg yolks

1 tablespoon cornstarch

1 cup flaked coconut

½ cup chopped walnuts

In a medium saucepan, combine the half and half, butter, sugar, yolks and cornstarch. Bring to a boil over medium heat. Remove from the heat and stir in the coconut and walnuts. Cool to room temperature before frosting cake.