Preheat oven to 425. Spray a 9x13 pan with non stick spray
Mix mayonnaise and horseradish until blended.
Put breadcrumbs on a plate or shallow pie pan
Spread 3 tablespoons of mayo mixture all over each chicken breast.
Coat each piece of chicken with 1/4 cup of bread crumbs
Place chicken in prepared pan. Spray the top of the chicken wit cooking spray until crumbs are coated.
Bake at 425 about 20-25 minutes, depending on the thickness of the breasts. Chicken is done when cooked through and reaches an internal temperature of 165.