Pre-heat oven to 400°F or 200°C. Line a baking sheet with parchment paper and set aside. In a small bowl combine sauce ingredients and set aside.
Grill flatbreads for 4-minutes each side and transfer to a lined baking sheet.
Heat a grill pan over high heat. In a medium bowl, toss quartered Florida Grapefruit with olive oil and grill 1 minute each side and set aside.
Evenly distribute mozzarella, grilled Florida Grapefruit, chicken, sliced prosciutto and avocado over flatbread and season with salt and pepper.
Bake flatbread for 6 minutes until cheese is melted. Finish with fresh rocket and watercress. Drizzle with honey chilli sauce. Serve warm.