Process 1 slice of Panera Bread Three Cheese Bread into fine crumbs in a food processor. Measure out 1/2 cup and set aside.
Heat grill to medium-high heat, about 425°F.
Combine turkey, bread crumbs, apple butter, ketchup, onion, parsley, seasoning, salt, and pepper in small mixing bowl. Using your hands, mix gently, and form into 4 patties no more than 3/4 inch thick. If mixture is loose, form patties on sheets of wax paper to make it easier to transfer them to the grill. Coat burgers with cooking spray.
Brush grill grate and coat with oil. Grill burgers for 8 to 9 minutes, flipping after 5 minutes for medium-done (slightly pink, 150°F on an instant-read thermometer). Add 1 minute per side for medium-well done (160°F).
Toast remaining slices of Panera Bread Three Cheese Bread briefly on grill and serve burgers on the bread with your choice of condiments (we used mayo).
Tip: If you don’t have apple butter, replace it with applesauce drained in a colander for 15 minutes. For a cheeseburger, melt slices of sharp cheddar on the burgers during the last minute of cooking.