From Longman Dictionary of Contemporary Englishdouble boilerˌdouble ˈboiler noun [countable] DFUa pot for cooking food, consisting of one pan resting on top of another pan with hot water in it
Examples from the Corpus
double boiler• In the top of a double boiler over hot water, melt the chocolate squares and the tablespoon butter.• Melt chocolate, best done on a double boiler, and add it to the egg white mixture. 