Grease and flour 15 inch jelly roll pan. Bake cake mix in pan at 350 degree oven for approximately 20 minutes. Cool.
Cook in saucepan 5 tablespoons flour and 1 1/4 cups milk until thick. Cream 1 cup sugar, 1 cup Crisco and 1/2 cup butter and add flour mixture. Put on top of cake.
Melt 1/2 cup butter and 3 ounce unsweetened chocolate. Beat 1 egg, 1 teaspoon vanilla, 2 1/2 tablespoons hot water and 1 1/4 cups powdered sugar. Add heated chocolate and butter mixture. Pour over cake. Cut into squares when cool and taste just like Hostess Ho Ho's.
