Nacho Casserole

1 pound lean ground beef

1 large onion, -- chopped

1 16 oz can refried beans

1 4 oz can chopped green chiles, -- drained

1 cup shredded cheddar cheese

1 1/2 cups shredded Monterey jack cheese

1 cup taco sauce

1/4 cup chopped green onions -- including tops

1 4 oz can chopped ripe olives, -- drained

1 ripe avocado, -- mashed

1 cup sour cream

tortilla chips

Brown beef and crumble in a large skillet. Add onions and cook until transluce nt. Season to taste with salt and pepper. Spread refried beans in the bottom of an 11/13 inch baking dish; top with meat mixture. Sprinkle chiles, then che eses, then taco sauce over all. Bake at 400�F for 20 minutes. Remove from oven and sprinkle green onions and olives over all. Mound mashed avocado in the ce nter; top with sour cream. Serve with chips.