1Heat oven to 350° F. In 10-inch skillet, heat oil. Add onion; cook, stirring constantly, about 2 minutes or until tender. Stir in beef. In small bowl, mix chili powder, 1 tablespoon Bisquick mix and the water; stir into beef mixture. Stir in tomatoes and chilies; heat to boiling, stirring frequently.
2Pour beef mixture into ungreased 2-quart casserole. Stir 3/4 cup Bisquick mix, the cornmeal, milk and egg until well blended. Spoon over beef mixture. Top with bell pepper rings.
3Bake uncovered 35 to 40 minutes or until golden brown.