In frying pan brown your ground beef and drain the fat off. I like to mix everything together right in the pan I use to bake it in either a 8"x8" baking dish or 9"x13" cake pan depending on how large of a batch I am making. Combine browned ground beef, your can of tomatoe base, corn, beans and water then set aside. Preheat oven to 350°. While you oven is preheating follow the instructions on the instant mashed potatoes use the instructions for the amount of servings you need. Once the potatoes are done spoon them onto the top of the mixture you set aside. Top with slices of american cheese to cover. Cover with tinfoil and place in oven after 20 minutes remove the tinfoil and bake until cheese turns golden brown on the edges aproximately another 5-10 minutes.