Heat oven to 375°F. In 12-inch skillet, cook beef, onion powder, salt and pepper over medium-high heat 5 to 7 minutes, stirring frequently, until beef is brown; drain.
Stir vegetables and soup into beef; heat to boiling. Spoon into ungreased 2-quart casserole.
In small bowl, stir Bisquick™ mix, milk, and egg with wire whisk or fork until blended. Pour over hot beef mixture.
Bake uncovered 25 to 30 minutes or until crust is golden brown. Top with cheese. Bake 3 to 5 minutes longer or until cheese is melted.