Put the chicken in a sealable plastic bag and pour in the Caesar dressing. Seal well, shake to coat, then marinate in the fridge for at least 1 hour. If you're using wooden skewers, soak them in water for at least 30 minutes before cooking to prevent the skewers burning. Meanwhile, preheat or light the barbecue.
Thread the chicken onto the skewers, discarding the marinade. Cook on a medium-hot grill for about 15 minutes, turning regularly, until cooked through and no pink colour remains. Set aside and keep warm.
Butter both sides of the ciabatta slices. Toast on the barbecue for 1-2 minutes on each side, until golden. At the same time, grill the bacon for 5-10 minutes, until crispy, then cut into thin strips.
Take 4 serving plates and put 2 slices of toasted ciabatta on each one, then put a chicken skewer on top of each slice. Put 2 lettuce wedges on each plate, scatter over the bacon and serve with lemon wedges on the side.