Preheat the oven to 400°F (200°C).
Using a sharp knife, cut a pocket into the side of each chicken breast.
In a bowl, combine the spinach, cream cheese, mozzarella, garlic, and Parmesan cheese.
Mix until well combined.
Stuff the spinach mixture into each chicken breast pocket.
Secure with toothpicks if needed.
Rub the chicken breasts with olive oil.
Season with paprika, Italian seasoning, salt, and pepper.
Place the chicken in a lightly greased baking dish.
Bake for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C).
Let rest for 5 minutes before serving.
Remove toothpicks and serve warm.