Preheat oven to 350 degrees F (175 degrees C).

In a large skillet, brown ground beef over medium heat.

Drain off any excess grease.

Add butter to the skillet.

Add chopped onion, minced garlic, and chopped green pepper to the skillet.

Cook until the vegetables are tender.

Stir in the condensed cream of mushroom soup, condensed tomato soup, and water.

Heat the mixture through.

Add the cooked and drained spaghetti to the sauce.

Stir in 1/2 cup of shredded cheddar cheese.

Transfer the spaghetti mixture to a 3-quart casserole dish.

Top with the remaining 1/2 cup of cheddar cheese.

Bake in the preheated oven for 30 minutes, or until bubbly and the cheese is melted and lightly browned.