CREAM-FILLED CHOCOLATE CAKE

Steps:

• Prepare cake batter according to package directions; pour into a greased 15x10x1-in. baking pan. Bake at 350° for 20-25 minutes or until a toothpick inserted in the center comes out clean. Cool on a wire rack. , Meanwhile, for filling, combine flour and milk in a saucepan until smooth. Bring to a boil over medium heat, stirring frequently. Cook and stir for 2 minutes; remove from the heat and cool completely. , In a bowl, cream butter, shortening, sugar and salt until fluffy. Add flour mixture; beat until fluffy, about 4 minutes. Spread over cake. Freeze for 15 minutes. For frosting, beat butter, cocoa and vanilla in a bowl until fluffy. Beat in sugar and water. Spread over filling. Store in the refrigerator.