Preheat oven to 350 degrees F (175°C).
Season chicken breasts with salt and pepper, then place them in a 9x13 inch baking dish.
In a medium bowl, combine the chopped spinach, artichoke hearts, Parmesan cheese, mayonnaise, sour cream, and minced garlic until thoroughly blended.
Evenly spread the spinach and artichoke mixture over the chicken breasts, ensuring they are completely covered.
Place one slice of mozzarella cheese on top of each chicken breast.
Bake for 35-40 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and is no longer pink in the center.