In A Nonstick Skillet, Saute Ham For 4-5 Minutes Or Until Browned; Drain And Pat Dry. In A Greased 2-Qt. Baking Dish, Layer The Turkey, Cheese And Ham; Set Aside. In A Saucepan, Saute The Onion In Butter Until Tender. Stir In The Flour, Mustard And Nutmeg Until Blended. Gradually Stir In Milk. Bring To A Boil; Cook And Stir For 2 Minutes Or Until Thickened. Pour Over Ham. Combine Topping Ingredients; Sprinkle Over The Top. Bake, Uncovered, At 350 Degrees F For 25-30 Minutes Or Until Golden Brown And Bubbly.