Spray 9"x11" casserole dish with non-stick cooking spray.
Place chicken breasts in dish, in single layer.
Using small mixing bowl, combine shredded cheese, mayonnaise, ranch mix, mustard, and lemon juice. Stir thoroughly then spread evenly over chicken breasts.
Evenly sprinkle breadcrumbs over chicken.
Spray with non-stick coating or oil (via mister).
Place in oven and bake for 30 minutes or until done.
Garnish with additional shredded cheese if desired.