In a saucepan combine all of the ingredients for the BBQ sauce. Simmer uncovered for 10 minutes. Set aside.
Lightly grease the grates of an outdoor grill. Heat the grill to medium-heat heat. Add the chicken breasts to the grill and cook turning frequently. During the last 10 minutes of cooking baste the chicken breasts on both sides with the bbq sauce multiple times. Cook until the chicken has reached an internal temperature of 165 degrees F. During the last few minutes of cooking top each chicken breast with 2 slices of cooked bacon and 1 slice of pepper jack cheese. Cook until the cheese has melted.