1/3 c. butter
1/2 c. brown sugar
3 or more egg yolks
1 c. walnuts
1/2 tsp. vanilla

Melt together the butter and brown sugar. Add the egg yolks and mix well. Cook until thick, watching carefully to keep the mixture smooth. Add the walnuts and vanilla and spread on cake. Then frost with your favorite white frosting. I use this on a white cake with a boiled white frosting.