Mornay sauce is a classic French sauce named after the Duke of Mornay in the late 16th or early 17th century. The name itself is interesting, because Mornay is a mixture of melted cheese in a béchamel sauce, a cream sauce made from a roux. Yet, béchamel sauce had not been invented when Mornay sauce was first made. Thus it’s commonly thought that some sort of cheese sauce predated béchamel and was called Mornay sauce, but was later improved upon by mixing cheese with béchamel.

The classic Mornay sauce is composed of a mixture of gruyere and parmesan cheese, usually in a half and half ratio to cooked béchamel. The cheese melts quickly providing a delicious, savory sauce. The French may use Mornay sauce to top steamed vegetables, or on seafood and poultry dishes. It can also be mixed in with pasta to make a variant of macaroni or alfredo. Some people use a Mornay sauce as part of the layers of lasagna.

You can certainly change the cheeses you add to Mornay sauce to get different flavors in the end result. White cheddar is a common substitution, resulting in a sauce that will make some of the best macaroni and cheese you’ve ever tasted. Children who are picky about vegetables may enjoy them more if they are topped with white cheddar Mornay sauce.

When making Mornay sauce, you must use hard or semi-hard cheeses. Cheese like brie, or blue cheese are not the best choices. You can get away with some jack cheeses, and also hard goat cheeses. Just don’t try cream cheeses or fresh mozzarella as these won’t melt into that wonderful creamy consistency. Also the French tend to avoid any but white cheeses when making Mornay sauce. If you want to keep the sauce authentically French, don’t add orange or yellow cheddar cheese. On the other hand, some children may be bigger fans of an orange colored cheese sauce than they are of a white sauce.

Mornay sauce is not exactly a low fat sauce — a butter roux mixed with cream or whole milk, and whole milk cheese is going to pack some calories. You can lighten the calorie load a bit by using a low fat milk to add to the roux, and by using good low fat cheeses. Try a little bit less of the sauce than you might normally use, too, since this will lessen the overall calories. Sauces in France are used as accents to meals but not meant to obscure the flavors of good, fresh food.