Green Chili Casserole

3/4 cup chopped onion
2 tablespoons butter
1 can cream of mushroom soup
1 can water
1 can chopped green chilis
2 cups Cheddar cheese, shredded

Sauté onions in butter until clear. Place inside slow cooker. Mix in soup and water until well mixed. Add green chilis, stirring to mix. Cover with lid and cook on low setting for 7 to 9 hours or on high for 4 to 6 hours. Add cheese to slow cooker an hour before serving. Serve with tortillas and pinto beans.