Preheat the oven to 4oo degrees. Line a cookie sheet with aluminum foil or parchment paper and set aside.
Lay chicken breast on the baking sheet.
In a small bowl, combine the mayonnaise and ranch dressing. Spread on each chicken breast.
Top the chicken with shredded cheese.
Bake uncovered for 30-40 minutes or until the internal temperature is 165 degrees. Allow to rest 10 minutes lightly covered with foil. Slice and serve.