Dice zucchini & squash into bite sized pieces. Add them to a zip lock bag with the onions & peppers. Add the avocado oil & McCormick's seasoning. Zip the bag closed & smoosh all around to ensure every piece is coated evenly. Dump the bag into a 9 x 13 casserole dish that's been sprayed with cooking spray.
Lay the chicken breasts on a cutting board and set a sheet of plastic wrap over the top. Gently pound out the chicken to make them uniform in size, about 3/4 of an inch thick.
Lay the chicken over the veggies in the casserole dish. Sprinkle the chicken with seasoned or garlic pepper.
Spoon about a tablespoon of basil pesto over each breast, making sure to cover each piece of chicken.
Sprinkle the bread crumbs over the whole casserole dish. Spray a light layer of cooking spray over the crumbs.
Bake at 350 degrees for 45 minutes, or until the chicken is 165 degrees on an instant read thermometer. Enjoy!