Place chicken in a lg shallow baking dish. Poke holes in each chicken and pour worcestershire sauce over chicken. Turning to coat. Refrigerate 1 hr.
Meanwhile cook bacon in lg skillet over med-high heat. Drain on paper towels. In medium skillet, melt butter over medium heat. Saute mushrooms until soft. Preheat oven to broil.
Drain chicken of marinade. Broil chicken in baking dish 5 min each side. Top each chicken breast w/ 2 slices bacon. Sprinkle w/ cheese. Broil until cheese is melted. Remove from oven and top w/ mushrooms and dressing.