1. Preheat oven 350 degrees. Spray a large baking dish (I use a deep 11×7 inch pan) with cooking spray and set aside. Peel potatoes and chop into large, evenly sized pieces.
2. Boil potatoes for 15-20 minutes or until soft when pierced with a fork. Drain the potatoes and beat with a mixer until smooth. Add milk, cream cheese, sour cream, parsley, garlic salt, and pepper. Beat at at low speed until nice and creamy.