Chicken Tetrazzini

8 oz. spaghetti
2 Tbsp butter
1/4 cup chopped onion
1/2 green bell pepper (optional)
2 c. cooked chicken
4 oz. fresh mushrooms or canned mushrooms
1 can cream of mushroom soup
1 1/2 cups milk
1 c. Monterey Jack cheese
salt and pepper to taste
Parmesan cheese

Break spaghetti in half and cook as directed. Chop onion and pepper, cube/shred chicken. Melt butter and cook onion, fresh mushrooms (canned can be added when tossed) and bell pepper until tender. Toss all ingredients, except Parmesan cheese. Place mixture into a casserole dish, covered at 350 degrees for 30-45 minutes until bubbly. Grate Parmesan cheese over casserole.