preheat oven to 350°

saute onion, ground beef and garlic; drain

blend in tomatoes, taco seasoning, chilies and olives. Simmer for 10 minutes

grease 9x13 inch pan, layer half of the tortilla chips on the bottom of pan

add all the meat mixture, then mozzarella and sour cream

top with remaining chips

bake until heated through, about 30 minutes

sprinkle with cheddar cheese; continue baking until cheese melts

let stand 5 minutes before serving