Spray the inside of a slow cooker with cooking spray. Add chopped potatoes. Cover and cook 2-3 hours on high or 5-6 hours on low.Add sour cream, milk, garlic, salt, and pepper to potatoes. Use a hand mixer to blend together all ingredients. (Please see note below recipe!) Give them a taste and add more salt if desired. Serve plain, or with any favorite toppings such as gravy, or cheese and bacon. OR - check out my brand new variation - Slow Cooker Buttery Garlic Herb Mashed Potatoes!