1Heat oven to 350ºF. Grease square baking dish, 8x8x2 inches.
2Mix Bisquick, milk, mustard and egg until blended. Pour half of the batter into baking dish. Top with half of the ham and 1/2 cup of the cheese. Top with remaining ham. Pour remaining batter over ham.
3Bake 45 to 50 minutes or until golden brown and set. Sprinkle with remaining 1/2 cup cheese. Let stand 5 minutes before cutting. Cut into 9 squares; cut each square diagonally in half.