In a medium saucepan cook cabbage, covered, in a small amount of boiling, lightly salted water for 5 minutes. Drain and set aside. In the same pan melt margarine or butter. Stir in flour, 1/2 teaspoon salt, and 1/8 teaspoon black pepper. Add milk all at once. Cook and stir over medium heat until thickened and bubbly. Stir in sweet pepper, cheese, and onion. Stir until cheese is melted. Remove from heat.
Place 3 cups of the corn bread in a 2-quart casserole. Top with cabbage, sauce, and remaining corn bread. Bake, uncovered, in a 375 degree F oven 30 to 35 minutes or until heated through. Makes 8 side-dish servings.