For nutty cheese flavor, try Asiago in this casserole. Like Parmesan, Asiago is an Italian cheese aged for grating. Asiago that is less than a year old is a lovely table cheese.
Dough-topped casseroles must be assembled while the filling is piping hot to ensure even cooking from underneath as well as on the surface. Otherwise, the topping will bake at the surface but remain doughy next to the filling. As the filling heats, prepare the dough so that everything is ready to assemble at once.