Techniques
What is mornay sauce?
The short answer. Mornay sauce is a white sauce, made with a roux and milk, finished with melted cheese.
It is the sauce behind classic macaroni and cheese. Make a roux, whisk in milk until it thickens, then take the pot off the heat before stirring in the cheese a handful at a time.
Cheese added over high heat can turn grainy and split. Shredding the cheese from a block also helps, because bagged shreds carry starch that keeps the sauce from going smooth.
Where it shows up in our recipes
Question
Why did my cheese sauce turn grainy?
It was too hot when the cheese went in, or the cheese was pre-shredded. Take the pot off the heat and use cheese shredded from a block.