01 - Preheat the oven to 400°F. Lightly grease a baking dish with olive oil or cooking spray.
02 - In a mixing bowl, combine the chopped spinach, softened cream cheese, shredded mozzarella, grated Parmesan, chopped sun-dried tomatoes, minced garlic, ¼ teaspoon salt, and ¼ teaspoon black pepper. Stir until all ingredients are evenly distributed.
03 - Using a sharp knife, carefully cut a deep pocket into the side of each chicken breast, ensuring you do not slice all the way through. Keep the opening as narrow as possible to hold the filling securely.
04 - Generously fill each chicken breast pocket with the spinach and cheese mixture. Use toothpicks to pin the openings shut if needed to keep the filling enclosed during cooking.
05 - In a small bowl, combine the Italian seasoning, paprika, ½ teaspoon salt, and ¼ teaspoon black pepper. Rub this seasoning blend evenly over all surfaces of each stuffed chicken breast.
06 - Heat 1 tablespoon of olive oil in a large ovenproof skillet over medium-high heat. Place the stuffed chicken breasts in the skillet and sear for 2 to 3 minutes per side until a golden-brown crust forms.
07 - Transfer the skillet directly into the preheated oven, or move the chicken breasts to the prepared baking dish. Drizzle the remaining 1 tablespoon of olive oil over the top. Bake for 20 to 25 minutes until the internal temperature of the thickest part reaches 165°F.
08 - Remove the chicken from the oven and let it rest for 5 minutes. Carefully remove any toothpicks before serving. Plate and accompany with a crisp green salad or garlic roasted vegetables.