1 prepared yellow cake (9 x 13 inch size)
1 c. sugar
1/2 c. Crisco
1 tsp. vanilla
1 c. milk
5 tbsp. flour
1/2 tsp. salt
1/2 c. butter

Mix flour with milk and boil until thick. Cool, then beat until fluffy and add the other ingredients, except prepared cake. Beat well as you add each ingredient. Put between split layers of cake. Let stand at least 1 day to develop flavor. Refrigerate.