01 - Preheat the oven to 400°F. Lightly grease a baking dish with cooking spray or a small amount of olive oil.
02 - In a mixing bowl, combine crumbled feta cheese, chopped spinach, minced garlic, cream cheese, dill (if using), salt, and black pepper. Mix until thoroughly blended and uniform in texture.
03 - Using a sharp knife, slice a horizontal pocket into the side of each chicken breast, taking care not to cut completely through to the other side. Open pockets gently to create space for filling.
04 - Generously fill each chicken breast pocket with the spinach and feta mixture. Secure openings with toothpicks to prevent filling from escaping during cooking.
05 - Rub the outside of each stuffed chicken breast with olive oil. Season generously with additional salt and black pepper on all sides.
06 - Place the stuffed chicken breasts in the prepared baking dish, arranging them in a single layer with space between each piece for even cooking.
07 - Bake for 25–30 minutes, or until the chicken is completely cooked through and juices run clear when pierced. Internal temperature should reach 165°F.
08 - Carefully remove toothpicks from the chicken breasts. Serve immediately with fresh lemon wedges on the side for squeezing over the cooked chicken.