1 pkg yellow cake mix
1 pkg (3.4 oz) instant vanilla pudding mix
1/2 c shortening
1 c water
Filling: 5 Tbsp flour, 1 c milk 1/2 c margarine, softened, 1/2 c shortening, 1 c sugar, 1 tsp vanilla, 1/2 tsp salt.
Beat cake mix, pudding mix, and shortening on low til crumbly. Add water and eggs. Beat on med for 2 min. Pour into a greased 9 x 13 pan. Bake at 350 for 30-35 min. Cool 10 min. Put cake on a wire rack. Meanwhile, in a saucepan, mix flour and milk til smooth. Bring to a boil; cook and stir 2 min. Cool completely. In a bowl, cream butter, shortening, sugar, vanilla, and salt. Beat in milk mixture until sugar is dissolved. Split cake in half horizontally. Spread filling over bottom layer. Replace top layer and serve.