flan a term with two meanings. The one most familiar in Britain, as neatly given in the NSOED, is: ‘An open pastry or sponge case containing a (sweet or savoury) filling.’ A typical flan of this sort is round, with shortcrust pastry. It is either baked blind before the hot or cold filling is added, or baked with the filling. The filling, especially if it is a sweet one, may incorporate custard.
In France the term flan carries the first meaning described above, but often has the second meaning: a sweet custard which is baked in a mould in the oven until set, when it may be served in the mould or turned out. See also crème and crème caramel.