A Mornay sauce is a béchamel sauce with shredded or grated cheese added. Some variations use different combinations of Gruyère, Emmental cheese, white Cheddar or even Parmesan cheese. A Mornay sauce made with cheddar is commonly used to make macaroni and cheese.

The name origin of Mornay sauce is debated. It may be named after Philippe, duc de Mornay (1549–1623), Governor of Saumur and seigneur du Plessis-Marly, writer and diplomat, but a cheese sauce during this time would have to have been based on a velouté sauce as béchamel had not yet been developed.

Ingredients:

-1½ cups sauce béchamel

-1/4 tsp cayenne pepper

-¼ cup Parmigiano Reggiano, finely grated, combined with

-¼ cup gruyère cheese, finely grated

Procedure:

-In a saucepan, combine the 'sauce béchamel' and the cayenne.

-Stirring constantly, heat the sauce until it comes to a simmer.

-Remove the saucepan from the heat and stir in the grated cheese.

-Taste for seasoning and adjust with salt and pepper if necessary.

-If not served immediately, you may dot the surface with butter to prevent a skin from forming.

More Info: en.wikipedia.org