In a small bowl, mix the mayo, salt, pepper, and garlic powder until combined.
Cut the chicken breast into thirds and place them in the food processor with the chopping blade. Pulse until they are in approx 1/2 inch pieces. Then empty the chicken and change the blade to the vegetable chopping attachment. Use this to chop the onion.
Place chicken, tomatoes, onion, and mozzarella in a large bowl and fold in the mayo mixture until combined. Gently stir in the basil to finish.
Serve on toast, lettuce wraps, in a hollowed out roll, a tomato, or on sliced cucumber.
Makes approx 8 servings.
Recipe by The Pinning Mama at https://www.thepinningmama.com/caprese-chicken-salad/