In French cuisine, it is often used in fish dishes.

In American cuisine, a Mornay sauce made with cheddar is commonly used for macaroni and cheese.

It may be named after Philippe, duc de Mornay (1549–1623), the French diplomat and writer, but a cheese sauce during this time would have to have been based on a velouté sauce because béchamel had not yet been developed,[3] so the cheese sauce that the Duke would have known was different from the contemporary version.

[4] Sauce Mornay does not appear in Le cuisinier Royal, 10th edition, 1820, perhaps because sauce Mornay is not older than the seminal Parisian restaurant Le Grand Véfour, where sauce Mornay was introduced.

[3] Mornay sauce is a smooth sauce made from béchamel sauce (butter, flour, milk), grated cheese, salt, and pepper, and often enriched with egg yolk.