1 1/2 pounds lean ground beef
1 medium onion, chopped
1 envelope cheese sauce mix
1/4 cup water
1 can cream of mushroom or cream of chicken soup
1 can stewed tomatoes (15 oz)
2 tablespoons tomato paste
1 cup shredded cheddar cheese
8 ounces macaroni, cooked just until tender

Brown ground beef and onions. Combine all ingredients, except shredded cheese and macaroni, in the slow cooker/Crock Pot. Cover and cook on low for 6 hours. Add cheese and hot cooked macaroni and continue cooking for about 15 to 30 minutes longer, or until the cheese has melted and the dish is heated through.