Crock Pot Mashed Potatoes

5 lbs potatoes, peeled and quartered (about 15 medium)
6 ounces cream cheese
1 cup sour cream
2 teaspoons onion powder
1 teaspoon salt
1/2 teaspoon pepper
2 egg whites, slightly beaten
1 tablespoon butter

Cook potatoes in large pot of boiling water until tender.
Mash until there are no lumps.
Add cream cheese, sour cream, onion powder, salt, pepper and egg whites; blend well.
Cool slightly, place in removable liner of your crock pot and place in the refrigerator.
Take out of refrigerator about 3 1/2 hours before you plan to serve them.
Place in crockpot and dot with butter.
Cook on LOW for 3 hours, stirring once or twice.