HEAT oven to 350°F. Spray a 13 x 9-inch baking dish with no-stick cooking spray. Heat water, butter, garlic salt and onion salt to boiling in a 6-quart Dutch oven or saucepan. Remove from heat. Add cream cheese, milk and sour cream, stirring until cream cheese is dissolved.
STIR in potato flakes, mixing until all ingredients are well combined. Spread mashed potato mixture into prepared pan.
SPRINKLE with paprika and bake 1 hour or until bubbling around edges and golden brown. Top with chopped bacon and parsley, if desired.
To make with Pet Evaporated Milk: Heat 7 1/2 cups water with butter, garlic salt and onion salt. Replace 2 cups milk with 1 (12 oz.) can Pet Evaporated Milk.
TIP Before adding paprika and baking, potato mixture can be covered and stored in the refrigerator for up to 48 hours. Sprinkle with paprika and bake as directed above.