Fry bacon in a Dutch oven until crisp; remove bacon, reserving 2 tablespoons drippings. Crumble bacon and set aside.
Saute onion in reserved drippings until tender;
Stir in milk, cream corn, salt, mash potatoes,cheddar cheese, pepper jack cheese, green chilies and pepper to taste; continue to cook, stirring frequently, until heated through. Sprinkle with crumbled bacon and sliced avocado slices and serve.