The key to this recipe is the sauce. It is important to continuously stir the sauce with a rubber scraper throughout the entire process. Make sure to get into the corners of the pan.
Mix potatoes, ham and onion in greased 2 1/2-quart casserole. Set aside.
To make sauce:
In 2-quart saucepan on Wolf cooktop over medium heat, combine milk, butter, cornstarch, salt and pepper. Cook and stir 5 minutes or until smooth and thickened. Pour hot sauce over potato mixture. Place oven rack to rack position 2. Place casserole on rack. Close oven door. Set oven to convection humid mode at 345°F (175°C). Bake 1 hour or until golden brown and bubbly. Remove from oven and allow to cool for 15 minutes before serving.