Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 2 quart (8 inch round) casserole dish.

In a medium saucepan, bring 1 cup of water to a boil. Stir in instant rice, cover and remove from heat. Let sit for 5 minutes.

In a medium skillet over high heat, brown ground beef with onions and green pepper. Stir in diced tomatoes, tomato sauce and chili powder. Simmer for 20 minutes.

Stir cooked rice into the beef mixture. Mix in the corn, salt and pepper.

Pour the mixture into prepared casserole dish. Cut the American cheese slices in half and place over the top.

Bake in preheated oven for 15 to 20 minutes or until cheese is melted and bubbly.