Heat oven to 350°F. Reserve 1 cup French-fried onions for topping.
In 5-quart Dutch oven, mix remaining onions, the broccoli, cream cheese, bell pepper and pepper sauce. Cover; cook over medium-low heat about 20 minutes, stirring once halfway through cooking, until sauce chips are melted. Transfer to ungreased 2- to 3-quart casserole.
Bake uncovered 20 to 25 minutes or until vegetables are tender. Sprinkle reserved onions around outer edge of casserole; bake 5 minutes longer.