As you have undoubted surmised by now, I am unabashedly partial to Italian cuisine. Even so, I will be among the first to admit Italy has no monopoly on foods that taste good. Anyone who enjoys eating as much as I do knows that every country – if not every region within every country – can lay claim to some culinary masterpiece. In no particular order, after Italian, my favorite ethnic cuisines are German, Greek, Spanish, Asian, Indian, English, Polish, Middle-Eastern and, of course, French.
I found a most plausible explanation in a Blog posted by Lydia Clarke in 2013. The following three paragraphs are an edited version of Ms. Clarke’s article. You can (and should, it’s less than a page long) read the entire piece at acclero.com.
In 1651, chef La Varenne wrote Le Cuisinier François, considered to be the foundation of modern French cuisine. This highly influential book was one of the first to set down codified, systematized rules and principles of food preparation.
By the late 1890s, French cuisine was firmly ensconced as the preferred food of aristocrats and the upper classes in both Europe and the United States. In the early twentieth century, Georges Auguste Escoffier updated La Varenne’s rules and principles for preparing food and established a new system for the kitchen. He divided the kitchen into five stations, each responsible for different components of a dish. His system, along with the publication of Le Guide Culinaire in 1903, cemented France’s place in culinary history. Culinary schools still teach it, and most highly-rated restaurants still use it.
So while they might not have invented cooking, the French were the first and the best at creating systems and rules for cooking, writing them down, and passing them on. That's why professionals and amateurs alike sauté instead of "cook quickly in oil", julienne instead of "cut into thin strips", and purée instead of "blend into liquid".
But, let’s get back to Flan. The French “invented” Crème Brûlée in the 17th century (apparently a lot happened in the culinary world in France in the 17th century). Somewhat later, a version of Crème Brûlée (with the caramelized sugar on top) evolved to become Crème Caramel (with the caramelized sugar on the bottom). Over time, Latin American cultures adopted Crème Caramel and changed its name to Flan. So, in effect, all three desserts are the same, and share a French origin!
Nevertheless, being a typically stubborn Italian, I have posted three separate recipes for Crème Brûlée, Crème Caramel, and Flan (which also includes instructions for preparing a variation called Espresso Flan). They have been in my personal files for years, and have satisfied many dinner guests. I urge you to try at least one of them.
P.S. If you have already prepared any custard desserts you already know the importance of adding the hot liquid to the cooler eggs slowly and with constant stirring. It also is important to bake the custards slowly. Custard recipes range from 300° F to 350° F. I prefer the lower temperature. It takes a little longer, but the results are more reliable.