Heat the grill to medium-high and line a baking sheet with foil. Lay the chicken breasts upside-down on the foil, brush with 1 tbsp of barbecue sauce, then grill for 5 mins.
Turn the chicken breasts over, add the bacon rashers to the tray, then return to the grill for a further 5 mins.
Drizzle the chicken with the remaining barbecue sauce, sprinkle with cheese, then place back under the grill for 2-3 mins until the chicken is cooked through, the cheese is bubbling and golden and the bacon is crispy. Top the chicken with the bacon to serve.