Place the chicken breasts, one at time, between two pieces of plastic wrap or in a zip top bag. Using a meat pounder, pound the breasts to a uniform thickness and place. Season both sides with salt and pepper and place into the bottom of a greased 9” x 11” baking pan.
Cube the tomato and white onion into ¼” pieces. Remove the seeds and membrane of the jalapeño and finely. In a bowl, combine the vegetables, cilantro, lime juice, salt, and pepper.
Spread the mixture evenly over the chicken breasts and top with the shredded cheese.
Bake in a 375℉ for 35-40 minutes, until the internal temperature reaches 165℉. Let rest 5 minutes before serving.