What is béchamel sauce made of?

Béchamel sauce, also known as white sauce, is made from a white roux (butter and flour) and milk. It has been considered, since the seventeenth century, one of the mother sauces of French cuisine. It is used as the base for other sauces (such as Mornay sauce, which is Béchamel with cheese).

Balsamell or Besciamella is the Italian equivalent of the French Béchamel: a very simple white sauce of flour, butter, and milk. The sauce was originally from Renaissance Tuscany and was known as "Salsa Colla or Colletta" ("glue sauce") because of the gluey consistency of the sauce, and was brought to France by the chefs of Catherina de' Medici in 1533. Louis de Béchamel, Marquis de Nointel, was a financier who held the honorary post of chief steward to King Louis XIV. This sauce was prominent in Italian cooking texts of the Renaissance as "salsa colla", but was renamed much later in Le Cuisinier François, published in 1651 by François Pierre La Varenne (1615–1678), chef de cuisine to Nicolas Chalon du Blé, marquis d'Uxelles. The foundation of French cuisine, the Cuisinier François ran through some thirty editions in seventy-five years.