Halve the chicken breast into thin slices and salt and pepper all over. Add to a ziploc bag.
Mix the mayo and pesto until combined. Add to the bag and massage it into the chicken so all of the pieces are evenly coated. Marinated overnight, or for 3 hours for optimal flavor.
Turn a grill or grill pan to high heat and oil. Once heated, grill the chicken, around 5 minutes per side. Pull the chicken off the grill once the internal temperature reaches 155*F.
