Whereas a cake may remain fresh for several days after baking or even improve with keeping, a gateau usually includes fresh decoration or ingredients that do not keep well, such as fresh fruit or whipped cream.In France, the word 'gateau' designates various patisserie items based on puff pastry, shortcrust pastry (basic pie dough), sweet pastry, pate saglee, choux pastry, Genoese and whisked sponges and meringue...Cake is a Viking contribution to the English language; it was borrowed from Old Norse kaka, which is related to a range of Germanic words, including modern English cook." ---An A to Z of Food and Drink, John Ayto [Oxford University Press: Oxford] 2002 (p. English borrowed gateau from French in the mid-nineteenth century, and at first used it fairly indiscriminately for any sort of cake, pudding, or cake-like pie...Since the Second World War, however, usage of the term has honed in on an elaborate 'cream cake': the cake element, generally a fairly unremarkable sponge, is in most cases simply an excuse for lavish layers of cream, and baroque cream and fruit ornamentation...In France, Antonin Careme [1784-1833] is considered THE premier historic chef of the modern pastry/cake world.You will find references to him in French culinary history books.The word gateau is the modern French descendant of Old French guastel, 'fine bread'; which is probably of Germanic origin.
Most were probably rather sickly, made from cheap sponge filled with 'buttercream'..coated with fondant icing. French gateau are richer than the products of British bakers. These products naturally relaxed into rounded shapes.
The first cakes were very different from what we eat today.