01 - Preheat the oven to 400°F. Lightly grease a baking dish with olive oil.
02 - Pat chicken breasts dry. Using a sharp knife, carefully cut a horizontal pocket into the thickest side of each breast without cutting through completely.
03 - Season the chicken breasts inside and out with salt and freshly ground black pepper.
04 - Spoon 1 tablespoon of basil pesto into each pocket. Add sliced mozzarella and a few pieces of chopped sun-dried tomato to each breast.
05 - If needed, close the openings with toothpicks to secure the filling.
06 - Place stuffed breasts into the greased baking dish. Drizzle with olive oil and sprinkle grated Parmesan cheese over the top.
07 - Bake for 25 to 30 minutes, or until chicken reaches an internal temperature of 165°F and the cheese is melted and bubbly.
08 - Remove toothpicks, allow chicken to rest for 5 minutes, then slice and serve.