1 can tuna, drained
1 can any creamed soup
1 c. milk
1 c. uncooked macaroni
1 c. shredded cheese (save 1/4 c.)
1/2 c. chopped onion

In a 2 quart micro-safe casserole dish, mix all ingredients together. Cover and place in refrigerator overnight or at least 12 hours. Cook in microwave 15 to 20 minutes. Put 1/4 cup cheese on top until melted.