Place frozen biscuits on microwavable plate. Microwave uncovered on Medium (50%) 30 to 40 seconds or until soft.
Heat oven to 350°F. In medium bowl, beat eggs, milk and mustard with wire whisk until blended. Stir in potatoes, ham and cheese.
Spray 1-quart casserole with cooking spray. Cut each biscuit into 8 pieces; arrange evenly in dish. Pour egg mixture over biscuit pieces in dish. Press down with back of spoon, making sure all biscuits are covered with egg mixture.
Bake 40 to 45 minutes or until edges are golden brown and center is set. Let stand 5 minutes before serving.