Supposedly invented by Louis XIV’s maître d’hôtel, the Marquis de Béchameil, but the exact same sauce is recorded as being served in Cesena in the 14th century, 300 years before the French thought of it.
North Italians are very fond of it too, especially in its native Emilia-Romagna, where they put it on lasagna (lasagne in bianco), cannelloni and other oven dishes.
Also known as besiamella or balsamella.
Image by Michael Newman