What white sauce is used in traditional Bolognese lasagna?

Traditional Bolognese lasagna uses béchamel as its white sauce. Béchamel is a smooth sauce made from butter, flour, and milk, usually seasoned with salt and sometimes nutmeg.

In lasagne alla bolognese, béchamel is layered with green pasta sheets, ragù alla bolognese, and grated Parmigiano-Reggiano. The dish is associated with Bologna and the Emilia-Romagna region of northern Italy, where this combination is a classic preparation.

Béchamel is one of the five classic French mother sauces, and its earliest recognizable form appeared in a 1651 French cookbook. Mornay is a cheese-enriched derivative of béchamel, while Alfredo is a separate butter-and-cheese sauce. Hollandaise is an egg-yolk-and-butter emulsion, so none of those is the traditional white sauce in Bolognese lasagna.