Flan is a baked custard quite similar to crème caramel. It is typically made with eggs, cream or milk, gelatin and vanilla. Often, the custard is synonymous with crème caramel because it includes a layer of burnt or caramelized sugar on the bottom. Little ramekins of flan are then inverted, so the crunchy sugar is on the top.
This custard is quite popular in Latin American countries, but its origin is French. Often, flan served in Latin countries or restaurants does not have the caramel sugar layer, but instead is simply plain, more resembling Italian cream.
Sometimes, Latin American restaurants make the distinction between regular flan and dolce de leche, which served with a milk caramel sauce. Unlike crème caramel, the milk caramel sauce is added after the custard is baked and inverted. It is creamy rather than crunchy.
Flan enjoys great popularity in the US, in Latin American countries, and in the Philippines. It is also very popular in Japan, where some variants may be made with soy milk, since many native Japanese do not regularly consume cow milk.
There are also some instant flan mixes available. Thickening from these tend to come from the addition of either agar or gelatin. Authentic flan would probably not use either thickener, but would depend upon the addition of eggs to create the proper thickness. Most restaurant recipes, however, suggest gelatin.
While the custard is most often presented in individual portions, some make a large flan to serve at parties. This can be a particularly visually appealing dish, especially if either dolce de leche is added to the top, or if it has been baked over a layer of caramelized sugar. Some cooks even use a small blowtorch to further harden the sugar after baking. This provides a nice crunch that contrasts well with the creamy custard.
When flan is made in large portions, it is usually served in slices, and may be topped with whipped cream. The custard is usually served chilled, and care must be taken to refrigerate it, because it contains milk and eggs.