Preheat your oven to 375°F (190°C).
Carefully slice along the side of each chicken breast to create a pocket, ensuring not to cut all the way through.
Equally distribute the roasted red peppers, spinach, and mozzarella cheese among the chicken breasts, stuffing them.
Use toothpicks to secure the openings if necessary.
Mix olive oil, garlic powder, Italian seasoning, salt, and pepper in a small bowl. Brush this mixture over the chicken breasts, coating both sides.
Place the stuffed chicken breasts in a baking dish and bake for 25-30 minutes, or until the chicken is thoroughly cooked and no longer pink inside.