Preheat your oven to 375°F (190°C).
In a skillet, heat 1 tablespoon of olive oil over medium heat. Add minced garlic and sauté for about 1 minute until fragrant.
Add the chopped spinach to the skillet and cook until wilted, about 2-3 minutes. Remove from heat.
In a mixing bowl, combine the sautéed spinach, chopped roasted red peppers, and shredded mozzarella cheese. Stir well to combine.
Using a sharp knife, carefully create a pocket in each chicken breast by slicing horizontally, being careful not to cut all the way through.
Season the inside and outside of the chicken breasts with salt, pepper, and Italian seasoning.
Stuff each chicken breast with the roasted red pepper, spinach, and mozzarella mixture. If needed, secure the opening with toothpicks.
In the same skillet, add the remaining tablespoon of olive oil and heat over medium-high heat. Sear each stuffed chicken breast for about 3-4 minutes on each side until golden brown.
Transfer the seared chicken breasts to a baking dish and bake in the preheated oven for 20-25 minutes, or until the chicken is cooked through (internal temperature should reach 165°F/75°C).
Once done, let the chicken rest for a few minutes before slicing and serving.