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, fresh dill, salt, and black pepper. Mix thoroughly until all ingredients are well blended and forms a cohesive mixture.
03 - Using a sharp knife, carefully slice a horizontal pocket into the side of each chicken breast. Cut deeply but avoid cutting all the way through to create a cavity for stuffing.
04 - Generously fill each pocket with the spinach and feta mixture. Secure openings with toothpicks to prevent filling from escaping during cooking.
05 - Rub the exterior of each stuffed chicken breast with olive oil. Season generously with additional salt and freshly ground black pepper on all sides.
06 - Place the stuffed chicken breasts in the prepared baking dish, spacing them evenly to ensure proper heat circulation.
07 - Bake for 25 to 30 minutes, or until the chicken is completely cooked through and the juices run clear when pierced. The internal temperature should reach 165°F.
08 - Carefully remove toothpicks from the chicken. Serve immediately with fresh lemon wedges on the side for squeezing over the chicken.