flan (n.) Look up flan at Dictionary.com
"open tart," 1846, from French flan "custard tart, cheesecake," from Old French flaon (12c.), from Medieval Latin flado, probably a Germanic borrowing (compare Frankish *flado, Old High German flado "offering cake," Middle High German vlade "a broad, thin cake," Dutch vla "baked custard"), from Proto-Germanic *flatho(n), akin to words for "flat" and probably from PIE root *plat- "to spread" (see place). Borrowed earlier as flawn (c.1300), from Old French.