Party Mashed Potatoes
["5 lb. potatoes", "1/2 c. margarine", "2 (3 oz.) pkg. cream cheese, softened", "1 c. sour cream", "4 oz. extra sharp Cheddar cheese, shredded", "1/2 c. grated Parmesan cheese", "4 green onions, chopped", "1 tsp. pepper"]
["Cook potatoes until tender.", "Mash while hot.", "Add remaining ingredients and beat well.", "Cover and store in refrigerator (up to 2 weeks).", "On party day, remove casserole from refrigerator 1 hour before baking time.", "If desired, fluff up potatoes with a little milk.", "Bake, uncovered, at 350\u00b0 for 45 minutes or until heated through."]
["potatoes", "margarine", "cream cheese", "sour cream", "extra sharp", "Parmesan cheese", "green onions", "pepper"]