Preheat oven to 375°F (190°C).
Carefully slice a pocket into each chicken breast, making sure not to cut all the way through.
Stuff each chicken breast with roasted red peppers, spinach, and mozzarella cheese. Secure with toothpicks if needed.
In a small bowl, mix olive oil, garlic powder, Italian seasoning, salt, and pepper. Brush the mixture over the chicken.
Place the chicken in a baking dish and bake for 25-30 minutes or until fully cooked and no longer pink inside. Remove from the oven, let rest for a few minutes, then serve and enjoy!