Yorkshire Pudding Day is always celebrated on October 13th in the USA.
The Yorkshire pudding is a staple of the British Sunday lunch and in some cases is eaten as a separate course prior to the main meat dish. This was the traditional method of eating the pudding and is still common in parts of Yorkshire today. Because the rich gravy from the roast meat drippings was used up with the first course, the main meat and vegetable course was often served with a parsley or white sauce." (Bechamel Sauce)
Béchamel sauce (English: /bɛʃəˈmɛl, beɪʃəˈmɛl/ French: [beʃamɛl]), also known as white sauce, is one of the mother sauces of French cuisine and is used in many recipes of Italian cuisine, for example lasagne. It is used as the base for other sauces (such as Mornay sauce, which is Béchamel with cheese). It is traditionally made by whisking scalded milk gradually into a white flour-butter roux (equal parts clarified butter and flour by weight). Another method, considered less traditional, is to whisk kneaded flour-butter (beurre manié) into scalded milk. The thickness of the final sauce depends on the proportions of milk and flour. wikipedia
It is often claimed that the purpose of the dish was to provide a cheap way to fill the diners - the Yorkshire pudding being much cheaper than the other constituents of the meal - thus stretching a lesser amount of the more expensive ingredients as the Yorkshire pudding was traditionally served first."