Dish with a topping of breadcrumbs and cheese (6)
I believe the answer is:
gratin
(Other definitions for gratin that I've seen before include "Dish covered with grated cheese" , "Au . . . . . . - cooked with a crust of melted cheese" , "Cooked covered in grated cheese or breadcrumbs" , "A dish cooked with grated cheese on it" , "Grated cheese or breadcrumbs on a dish" .)