Cheesy Burger and Bean Dip

1/2 lb. lean ground beef
1 small onion, finely chopped
1 can (16 oz) refried beans - regular or fat free
1 jar chopped chiles
1 cup prepared chili sauce
2 cups shredded Monterey Jack cheese
8 oz. sour cream
thinly sliced black olives, optional
Saute the ground beef and onion in a skillet. Drain off the fat and place the beef mixture in a crockpot. Stir in the refried beans, chiles, chili sauce and shredded cheese. Cover and cook on low for 3 to 4 hours. Just before serving, stir in the sour cream and black olives (if using). Serve warm with tortilla chips or corn chips.