1Heat oven to 375°F. Grease 13x9-inch (3-quart) glass baking dish or spray with cooking spray. In 10-inch nonstick skillet, cook ham, bell pepper, onion and mushrooms 3 minutes, stirring frequently.
2Spread 3 cups of the cereal in baking dish. Sprinkle with ham mixture; top with cheese. In medium bowl, stir Bisquick® mix, milk and eggs with fork until well blended. Pour evenly over cheese. Sprinkle with remaining cereal.
3Bake uncovered 25 to 30 minutes or until knife inserted in center comes out clean.