Preheat the oven to 400F.Line a baking sheet with aluminum foil or parchment paper (for easy clean up).Divide and sprinkle the cheese evenly between the two pita breads. Bake in the oven for 5-7 minutes, until the cheese is melted and lightly golden.Toss the shredded lettuce with mayonnaise.Cut each pizza into 4 portions. Arrange chicken on each slice, followed by bacon. Top with shredded lettuce, tomato slices and avocado. Season with salt and pepper.Serve immediately.