Flan: from French flan, from old French flaon, from Medieval Latin flado, a Germanic borrowing from Old Germanic "flado" offering cake".
Flan In Ancient Rome
Flan first shows up in ancient Rome. Chickens were domesticated and kept for laying eggs in ancient Rome, although chicken eggs were the least favorite of the Romans who preferred just about any other kind of egg over chicken eggs. The Romans experimented with many new recipes, trying everything from stuffed field mice to deviled snake eggs. They used eggs for binders in various recipes and eventually developed a concoction now known as flan. One of their specialties was eel flan. Roman flan was a savory dish, not a sweet dish, but they also had a very palatable sweet flan that was flavored with honey.
Flan in Medieval Society
Even though the Romans were eventually driven out of Europe, their customs were so deeply embedded in all societies that they continued to be practiced up to this day.
Flan in the Middle Ages was more likely to be based on chicken eggs, which were more popular with northern europeans than they had ever been with the Romans. Medieval flan often had a flour crust and was made with more eggs, so it would firm up quickly and not need to be refrigerated. Medieval refrigerators only worked in the cold winter months.
A savory medieval egg custard pie (i.e., with crust) was often flavored with almond milk, saffron, cinnamon, and rosewater. Some of the medieval recipes indicate that nutmegs and meat (usually fowl) would be included. In different European countries, the recipe would be customized with regional ingredients.
Flan in Early Spain
The Moorish influence on desserts in Spain during the 11th to 15th centuries cannot be discounted. The Arabian influence on flan would include almonds and honey as well as orange. In the 15th-century Spanish kitchen, rich creamery milk was most often used to prepare dessert dishes, with the result that flan quickly became the national dessert. Flan recipes eventually spread through Spain to Latin America.
Flan in Renaissance Europe
Published recipes for flan begin showing up in cookbooks in the 1600's.In Renaissance Europe, egg custards come into two basic types: The firm baked "still" custards and the pourable "stirred" custards. Stirred custards were usually made over a fire or on a stove top rather than in an oven. The egg mixture would be stirred as it was brought to a point just under boiling, resulting in a thickened liquid. Still custards were baked in a water bath in an oven (if they had one) until they formed a thicker gel. They may or may not have used a pastry crust. Meat was an infrequent treat for most people in the Middle Ages, but became more common in the Renaissance. Egg custards could thus be either sweet or savory.