Brown 1 pound ground beef and 1 large chopped onion. Add 1 package taco seasoning mix and 1 (8 ounce) can tomato sauce plus 1/2 cup water. Beat 2 eggs with 1 cup half & half. Add to meat mixture, stirring constantly. Place 1/2 large bag tortilla chips in 2 quart casserole. Top with 1/2 meat mixture and 1 cup grated cheese. Repeat layers. Microwave on high 8 minutes. Turn dish and microwave 7 minutes more. Top with 1 cup sour cream and 1/2 cup grated cheese. Microwave on high 2-4 minutes longer or until cheese melts.