Heat oven to 350°F. In 3-quart saucepan, place Brussels sprouts and enough water just to cover sprouts. Heat to boiling; boil 6 to 8 minutes or until crisp-tender. Drain; place in ungreased 2-quart casserole.
In same saucepan, melt butter over medium-high heat. Add onion; cook 2 to 3 minutes, stirring frequently, until crisp-tender. Add flour; cook until well blended (mixture will be thick). Gradually add cooking sauce until mixture is well blended. Heat to boiling, stirring constantly; boil and stir 1 minute. Remove from heat; stir in cheese until melted. Pour over Brussels sprouts in casserole; mix gently.
Bake uncovered 25 to 30 minutes or until hot and bubbly. Sprinkle with bacon.