floating island

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A dessert of soft custard with mounds of beaten egg whites or whipped cream floating on its surface.

Wiktionary

1. n. A French cold dessert consisting of an "island" of meringue, made of egg whites and sugar, floating in a "sea" of custard.

GNU Webster's 1913

1. adj. a dish for dessert, consisting of custard with floating masses of whipped cream or white of eggs.