1 (6 oz.) can tuna
1 1/2 c. pre-cooked instant rice
1 (8 oz.) can tomatoes
1/4 c. chopped onions
2 tbsp. low fat butter
1/3 c. shredded low fat Cheddar cheese

Combine all the ingredients in a 13x9 casserole dish. Sprinkle the cheese over the top of casserole. Dot the casserole with the butter. Bake in 350 degree oven for about 30 to 40 minutes.