4 egg yolks
2 1/2 c. icing sugar
3/4 c. butter
1/2 c. strong coffee
1 tsp. vanilla

In top of double boiler, blend egg yolks with 3/4 cup icing sugar. Cook over simmering water, stirring constantly until thickened. Remove from heat. Cream butter, add remaining icing sugar gradually beating until smooth and creamy. Blend in cooled egg yolk mixture, coffee and vanilla. Beat until well combined.