Set a skillet over medium-high heat, and coat with cooking spray. Add the mushrooms, and 1 tablespoon of mesquite seasoning; cook and stir until almost done. Remove the mushrooms the pan using a slotted spoon, and coat with more cooking spray. Add chicken and brown on both sides. Return the mushrooms to the pan, and season with another tablespoon of mesquite seasoning. Cook, turning as needed, until chicken is no longer pink in the center, about 5 minutes.
Once the chicken is done, remove it from the pan, leaving the juices and mushrooms in the pan. Place slices of mozzarella cheese on top of the chicken. Stir the soup into the mushrooms, and bring to a simmer. Season with oregano and salt. Pour over the chicken, and serve.