Brown ground beef and onion. In large bowl, mix soups and sauce, then add
ground beef mixture and stir well. Place a layer of chips in bottom of large casserole dish. Spoon portion of ground beef mixture over chips then sprinkle grated cheese on top. Repeat this process until complete, ending with layer of cheese. Bake in 350 - 375 oven (uncovered), for about 20-30 minutes, until bubbly hot.
Optional: Top with mound of sour cream, guacamole, raw onions, salsa, etc.