First, make the pesto sauce. Combine all of the ingredients in a food processor and puree it all together until it is a thick, chunky sauce. Set it aside. Then marinate the chicken. Stir the buttermilk, dried basil and dried onion together in a bowl. Then submerge the chicken in it and make sure both sides are coated. Let the chicken sit in the marinade for 15 minutes. While the chicken is marinating, pre-heat the oven to 375 and get out a small baking dish.

Remove the chicken from the marinade when it is done and let all of the excess drip off, then transfer it to the baking dish. Discard the remaining marinade. Season the chicken with a pinch of salt and pepper each, then smother each chicken breast with half of the pesto sauce. Place two slices of mozzarella on top of each chicken breast to cover them both almost completely. Bake the chicken for about 30 minutes. Then serve immediately with your favorite sides!