Sour Cream Chili Bake

1 Pound ground beef
1/4 Cup onion, chopped
1 (16 ounce) Can kidney beans, drained
1 (15 ounce) Can tomato sauce
1 Envelope taco seasoning mix
1 Cup cheddar cheese, shredded
3 1/2 Cups corn chips
1 1/4 Cups sour cream

Cook ground beef and onion until meat is browned and onion is tender; drain. Stir in beans, tomato sauce, taco seasoning mix and 3/4 cup cheese. Sprinkle 2 1/2 cups corn chips in bottom of 8� square baking dish. Cover with beef mixture. Bake at 350�F for 20 to 25 minutes. Spread sour cream over chili. Top with remaining corn chips and cheese and bake 3 to 4 minutes longer.