German Chocolate Icing(For Cake)

In a saucepan on medium heat, melt butter and sugar. Cook until sugar melts. In a separate bowl, stir milk and egg yolks well. Add milk/egg mixture to the butter/sugar mixture in the saucepan. Continue cooking on medium heat; stirring all the while until icing thickens. Remove from heat; add nuts, coconut, and vanilla. Leftover icing will keep several weeks if sorted in a covered container in the refrigerator.