Flan
mid 19th century: from French (originally denoting a round cake) from Old French flaon, from medieval Latin flado, fladon-, of West Germanic origin; related to Dutch vlade ‘custard’.
wiktionary
Borrowed around 1846 from French flan(“cheesecake, custard tart, flan”), or in some uses (in reference to Spanish/Latin American flans) later from Spanish flan (itself from the French), both from Old French flaon (whence also Middle English flaon, flaun(“pie; cake”)), from Late Latin fladonem, accusative of fladō(“flat cake”), from Frankish *flaþō(“flat cake”), from Proto-Indo-European *pl̥h₂t-(“broad, flat”), from Proto-Indo-European *pelh₂-(“to spread out, be broad, be flat”); compare German Fladen. Akin to Old High German flado(“flat cake, offering cake”). More at flathe.
Although the -n is generally believed to derive from the Late Latin accusative form (fladonem) of fladō(“flat cake”), it might alternatively derive from an inflected form of the Frankish word (such as the Frankish accusative *flaþan, or the like). For a similar case, see garden.
English, from a slip of the tongue by actor Nathan Fillion.
etymonline
flan (n.)
"open tart," 1846, from French flan "custard tart, cheesecake," from Old French flaon "flat-cake, tart, flan" (12c.), from Medieval Latin flado (10c.), which probably is from Frankish *flado or another Germanic source (compare Old High German flado "offering cake," Middle High German vlade "a broad, thin cake," Dutch vla "baked custard"), from Proto-Germanic *flatho(n) "flat cake," which is probably from PIE root *plat- "to spread." Borrowed earlier as flawn (c. 1300), from Old French.
