Prepare the Chicken:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Butterfly the Chicken Breasts: Use a sharp knife to carefully cut a pocket into the side of each chicken breast, being careful not to cut all the way through.
3. Season the Chicken: Season both sides of the chicken breasts with salt and pepper. Set aside.

Prepare the Filling:

4. Sauté the Spinach: Heat 1 tablespoon of olive oil in a pan over medium heat. Add the minced garlic and sauté for 1-2 minutes until fragrant. Add the chopped spinach and cook until wilted, about 3-4 minutes. Remove from heat and let it cool slightly.
5. Mix the Filling: In a bowl, combine the cooked spinach, crumbled feta cheese, cream cheese, oregano, basil, and red pepper flakes (if using). Stir until well combined.

Stuff the Chicken:

6. Fill the Chicken Breasts: Stuff each chicken breast pocket with the spinach and feta mixture, pressing gently to ensure the filling is evenly distributed. You may need to secure the opening with toothpicks to keep the filling in place.

Cook the Chicken:

7. Sear the Chicken: Heat 1 tablespoon of olive oil in an oven-safe skillet over medium-high heat. Add the stuffed chicken breasts and sear for 2-3 minutes on each side, until golden brown.
8. Bake the Chicken: Transfer the skillet to the preheated oven and bake for 25-30 minutes, or until the chicken is fully cooked (165°F or 75°C internal temperature).
9. Rest the Chicken: Remove the toothpicks (if used) and let the chicken rest for 5 minutes before serving.

Serve and Garnish:

10. Garnish and Serve: Optionally, sprinkle with fresh parsley for a burst of color and freshness. Serve the stuffed chicken with your favorite sides, such as roasted vegetables, mashed potatoes, or a simple salad.