Denoting or served in a cheese-flavoured white sauce:mornay sauce[postpositive]:cauliflower mornay...
The Oyster Bar offers a dizzying array of dishes from a half dozen rested on ice to a baked dish with spinach and mornay cheese sauce or lightly grilled oysters with bacon.
Noodle rolls filled with minced Tasmanian possum, topped with mornay sauce.
The lobster was split in half and then mixed with mornay and Sauce Americaine.
Origin
Perhaps named after Mornay, the eldest son of the 19th-century French chef Joseph Voiron, who apparently invented the sauce.