Fluffy Hard Sauce
["1/2 c. butter", "1 egg yolk", "2 c. sifted confectioners sugar", "1 tsp. vanilla", "2 stiffly beaten egg whites"]
["Fluffy Hard Sauce:", "Cream butter.", "Stir in egg yolk. Gradually cream in sugar until fluffy and light.", "Add vanilla. Fold in egg whites.", "Vary flavor with lemon or orange juice and grated peel or add 1 tablespoon of rum or brandy.", "Refrigerate until serving."]
["butter", "egg yolk", "confectioners sugar", "vanilla", "egg whites"]