Recipe for Memaw's Casserole

I remember eating this casserole at my grandmother, Memaw's, house since I was young.  Now this dish is often requested at my own house from my children and husband! I sometimes make double to have an extra one in the freezer.

1 lb spaghetti, cooked according to directions
1lb ground beef
1 cup chopped onion
1 green pepper, chopped
3 pieces of garlic, chopped
1 small can mushrooms, or sautee your own fresh ones (we omit these b/c of the kids hating mushrooms)
1 can corn
1 can diced tomatoes
1 can tomato sauce
1 cup water
2 cups sharp cheddar cheese, grated
3 T chili powder (not the spicy Indian kind, the mexican/american kind)
1 cup frozen peas

Sautee your onions, peppers, and garlic. Add the beef and brown. Drain. Add spices and salt and pepper to taste.  Add the tomato cans and let this simmer 20 minutes or more on low heat.  Add the peas, corn, and mushrooms and simmer a little longer.
 Add your cooked spaghetti to the ground beef mixture. 
In a long pyrex (9*13) put half the mixture down, top with 1 cup cheese, then put the other half over it.  Top with remaining cheese.  You can cover it and freeze it at this point or bake at 350 for 40 or so minutes until it's bubbly and the cheese is melted.