1Heat oven to 400ºF. Spray baking dish, 13x9x2 inches, with cooking spray.
2Brush chicken with 1 tablespoon of the mustard, then coat with Bisquick mix. Place 1 chicken breast half in each corner of pan. Place potatoes, bell pepper and onion in center of pan; brush vegetables with remaining mustard. Spray chicken and vegetables with cooking spray; sprinkle evenly with cheese and paprika.
3Bake 35 to 40 minutes, stirring vegetables after 20 minutes, until potatoes are tender and juice of chicken is no longer pink when centers of thickest pieces are cut.