1Heat oven to 450°F. In ungreased 2-quart casserole, mix contents of uncooked potatoes and sauce mix pouches (from potato mix box), boiling water, half-and-half, chicken, peas and mushrooms.
2Bake uncovered 30 to 35 minutes, stirring once, until potatoes are tender.
3In small bowl, mix remaining ingredients; sprinkle over potato mixture. Bake uncovered about 5 minutes longer or until light golden brown.