In a large skillet over medium heat, add the olive oil and minced garlic. Sauté for about 1-2 minutes until fragrant. Add the baby spinach and cook until wilted, about 3-4 minutes. Remove from heat and let cool slightly.
In a mixing bowl, combine the sautéed spinach and garlic mixture with the Parmesan cheese and half of the mozzarella cheese. Season with salt and pepper. Stir until well combined.
Preheat your oven to 375°F (190°C). While the oven is heating, place each chicken breast between two pieces of plastic wrap. Using a meat mallet or rolling pin, gently pound the chicken until it’s about 1/2 inch thick.
Take a prepared chicken breast and spoon about 2-3 tablespoons of the spinach and cheese filling onto one end. Carefully roll the chicken up tightly, starting from the filled end. Place the seam side down in a baking dish. Repeat with the remaining chicken breasts.
Once all the chicken is rolled and placed in the baking dish, sprinkle the remaining mozzarella cheese and breadcrumbs over the top.
Cover the baking dish with foil and bake in the preheated oven for 25 minutes. After 25 minutes, remove the foil and bake for an additional 15 minutes, or until the chicken is cooked through and the cheese is bubbly and golden.