This cake is best after is has been covered and refrigerated for one day.

1 box (2 layer) yellow cake mix (I use Duncan Hines Butter Recipe Golden)
5 tbsp. flour
1 c. milk
1 c. sugar
1/2 tsp. salt
1/2 c. vegetable shortening (I use Crisco)
1/2 c. butter
1 tbsp. vanilla

Prepare cake mix as directed on box and bake in a well-greased 9x13 pan. Cool 20 minutes. Then flop pan over on wax paper sprinkled with confectioners sugar. Cut in half lengthwise, and the cake is easier to handle, if you let it continue cooling for an hour or two.

To prepare filling, boil flour and milk in a saucepan until thick, stirring constantly. Combine sugar, salt, shortening, butter and the 1 tablespoon of vanilla in a bowl and beat until fluffy. Add milk mixture and beat until fluffy.

Put filling on one half of cake and place other half on top. Sprinkle confectioners sugar on top. Cover cake and store in refrigerator.