1 (18.25 ounce) box yellow or pineapple cake mix
1 small box vanilla instant pudding
3/4 cup vegetable oil
1 (12 ounce) can 7-Up, at room temperature
1 cup granulated sugar
1 heaping teaspoon cornstarch
1/2 cup margarine
1 (No. 2) can crushed pineapple
1 1/2 cups flaked coconut
1 teaspoon vanilla extract
1 cup coarsely broken pecans
Beat all ingredients together well for 2 minutes with electric mixer. Pour batter into 3 (8-inch) layer pans or a 15 x 10-inch jellyroll pan that has been greased and floured.
Bake at 325 degrees F for 25 to 30 minutes. Cool for 10 minutes, if in layer pans, and remove from pans to cool thoroughly on wire rack. Fill and frost.
Filling: Combine first 6 ingredients and cook over medium heat until thick. Remove from heat and add vanilla extract and pecans. Cool before spreading between layers and over cake. If using a 15 x 10-inch pan, leave cake in pan and spread frosting over top.
Note: Cake mixes no longer contain 18.25 ounces of cake mix. They are around 15.25 ounces. To extend the cake so that your recipe turns out properly, use our Cake Mix Extender recipe.