gratinate

from The Collaborative International Dictionary of English v.0.48

Gratinate \Grat"i*nate\, v. t. [F. gratiner, v.i., to form a
   crust.] (Cookery)
   To cook, as macaroni, in a savory juice or sauce until the
   juice is absorbed and a crisp surface forms.
   [Webster 1913 Suppl.]