Begin by preheating your oven to 375°F (190°C) to ensure it's ready for baking when needed.
In a medium-sized mixing bowl, combine the finely chopped spinach, ricotta cheese, grated Parmesan, shredded mozzarella, minced garlic, dried oregano, salt, and black pepper. Mix thoroughly until all ingredients are well incorporated into a creamy filling.
Prepare the chicken breasts by placing them on a cutting board. Using a sharp knife, carefully make a horizontal pocket in each breast, slicing through the thickest part but ensuring you do not cut all the way through to the other side.
Generously stuff each chicken breast with the spinach and ricotta mixture. If the opening is wide, you might use toothpicks to secure the edges and keep the filling from spilling out during cooking.
In a large, oven-safe skillet, heat the olive oil over medium heat. Once the oil is hot, add the stuffed chicken breasts and sear them for approximately 3-4 minutes on each side, or until they develop a beautiful golden-brown crust.
Once seared, carefully transfer the skillet to your preheated oven. Bake the chicken for about 20-25 minutes, or until the internal temperature reaches 165°F (75°C) to ensure it is fully cooked.
After baking, remove the skillet from the oven and let the stuffed chicken rest for about 5 minutes. This resting period allows the juices to redistribute, keeping the chicken moist.
To serve, spoon marinara sauce over each stuffed chicken breast and garnish with fresh basil leaves. This not only adds a pop of color but also enhances the dish's flavor profile.
Notes
Serve with garlic bread or a light salad for a complete meal.