Prepare the Chicken: Use pre-cooked chicken or grill fresh chicken breasts. To grill: brush lightly with olive oil, season with salt and pepper, and cook for 5–6 minutes per side until done. Slice thinly. Make the Pesto (if homemade): In a food processor, combine basil, nuts, garlic, Parmesan, olive oil, salt, and pepper. Blend until smooth. Adjust seasoning as needed.
Preheat the Oven or Grill: Oven: Preheat to 425°F (220°C). Grill: Preheat to medium-high heat.
Assemble the Flatbreads: Place flatbreads on a baking sheet or grill pan. Brush lightly with olive oil. Spread a generous layer of pesto over each flatbread. Add shredded mozzarella evenly. Top with sliced chicken and cherry tomatoes. Sprinkle with a little Parmesan and freshly cracked pepper.
Cook the Flatbreads: Oven method: Bake for 10–12 minutes until the cheese melts and the edges are golden and crisp. Grill method: Place directly on the grill and cook for 5–7 minutes, covered, until bubbly and slightly charred underneath.
Add the Finishing Touches: Remove from heat and let cool for a minute. Garnish with torn fresh basil leaves before serving.