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.