Preheat your oven to 400°F (200°C). Pat the chicken breasts dry and season both sides with salt and pepper (add garlic powder or Italian seasoning if desired). Heat olive oil in a skillet over medium-high heat. Cook the chicken for 6-7 minutes on each side until golden brown and cooked through (internal temperature should reach 165°F or 75°C). Remove the chicken from the skillet and let it rest for 5 minutes before slicing into thin strips. Lay out the flatbreads on a baking sheet. Spread a generous layer of basil pesto over each piece. Distribute the sliced chicken evenly over the pesto-covered flatbreads. Sprinkle shredded mozzarella cheese over the chicken, followed by halved cherry tomatoes. Top with grated Parmesan cheese. Bake in the preheated oven for 10-12 minutes until the cheese is melted and bubbly, and the edges are golden brown. Optionally, switch to broil for the last 1-2 minutes for a crispy top, watching closely to prevent burning. Carefully take the flatbreads out of the oven and let them cool for a minute. Slice into quarters or halves and garnish with fresh basil leaves if desired. Serve warm with a side salad or your favorite dipping sauce.