Easy Taco Pot Pie

1 pound lean ground beef
1 medium onion, chopped (1/2 cup)
2 jars (8 ounces each) Old El Paso® taco sauce
1 cup shredded Cheddar cheese (4 ounces)
1 cup Original Bisquick® mix
1/2 cup milk
1 egg

Recipe Directions
Heat oven to 400ºF. Cook beef and onion in ovenproof 10-inch skillet over medium heat, stirring occasionally, until beef is brown; drain. Stir in taco sauce. Sprinkle with cheese. Stir remaining ingredients until blended. Pour over beef mixture. Bake about 30 minutes or until golden brown.