1 lb. Mexican style Velveeta cheese
1/2 c. onion, diced (saute in 2 tbsp. butter)
1 jar Old English sharp Cheddar cheese
1/4 c. Cheez Whiz
1 (12 oz.) can stewed tomatoes
1 (4 oz.) can chopped green chilies, can use less

Put all the ingredients in a crock pot or microwavable dish and melt all together, stirring often. Serve hot with Tostado chips.