gratin vs griddle

gratin

noun
  • The top crust of a dish, consisting of breadcrumbs or grated cheese heated under a grill; the dish itself. 

griddle

noun
  • A stone or metal flat plate or surface on which food is fried or baked. 

verb
  • To cook on a griddle. 

How often have the words gratin and griddle occurred in a corpus of books? (source: Google Ngram Viewer )