Season chicken breasts with salt and pepper and place in a 9x13 baking dish.
In a medium bowl, combine the spinach, artichokes, Parmesan cheese, mayonnaise, sour cream, and garlic until well blended. Spread on top of the chicken breasts covering completely. Place a slice of mozzarella cheese on top.
Bake for 35-40 minutes or until chicken is no longer pink.