Cheese sauce

Béchamel sauce is one of the mother sauces of French cuisine. This sauce is made from a white roux (butter and flour) and milk, seasoned with ground nutmeg. The first recipe of a sauce similar to béchamel is in the book Le cuisinier françois by François Pierre de La Varenne in 1651, made with a roux, as in modern recipes. The name of the sauce was given in honour of Louis de Béchameil, a financier who held the honorary post of chief steward to King Louis XIV of France in the 17th century.

Source: Wikipedia