Cook potatoes in boiling water to cover 15 minutes or until tender. Drain.
Beat potatoes and next 3 ingredients at medium speed with an electric mixer until smooth. Stir in milk and remaining ingredients. Spoon into a lightly greased 2-quart baking dish. (Cover and chill 8 hours, if desired; let stand at room temperature 30 minutes before baking.)
Bake, uncovered, at 400° for 15 to 20 minutes or until thoroughly heated.
*Frozen mashed potatoes may be substituted. Prepare potatoes according to package directions for 4 servings. Proceed with recipe as directed. For testing purposes only, we used Ore Ida Mashed Potatoes.