Prepare cake mix and bake in a 23 cm by 33 cm cake pan. Let cool. Cream butter, Crisco, and sugar. Add milk, flour, and peanut butter. Blend and whip until fluffy. Spread on cooled cake. Refrigerate a few hours until filling is thoroughly chilled. Remove foil lid from can of frosting and microwave until the mixture thins and is pourable. Check at 5-8 second intervals by stirring. It probably won't take longer than 30 seconds. You don't want the filling warm. Pour frosting over chilled cake until evenly spread. Refrigerate again unil frosting is chilled. Enjoy! Diana ----