Heavenly Potatoes

6 med. potatoes - peeled, cubed, boiled until tender
1 sm. onion - minced
4 oz. cream cheese - softened, low-fat okay
1/2 cup sour cream - low-fat okay
1/2 cup grated cheddar cheese - low-fat okay
2 tsp. salt
1/4 tsp. garlic salt
3 Tbls. butter OR margarine - cut into small pieces
1/4 tsp. parsley flakes - for garnish
1/4 tsp. paprika - for garnish

Beat together all ingredients, except for butter, parsley, and paprika and spoon into a greased 9" X 9" X 2" casserole dish; dot top with butter; sprinkle parsley and paprika over top. Refrigerate for at least 1 hour, or overnight. Bake in a 400 degree oven for 35 minutes, or until warm throughout.