Step 1

Heat a medium sized saucepan over medium-high heat and when hot, add the butter. When the butter melts, add the flour and start whisking. You want to be careful not to let the butter burn or the flour to turn brown. It's only going to take a minute to a minute and a half for the roux to start turning a pale yellow.

Step 2

Slowly add the milk in a stream while constantly whisking and whisking some more. Bring the sauce to a boil and immediately lower the heat to a simmer and continue cooking for 3 to 4 minutes, being careful not to let the sauce burn by whisking frequently.

Step 3

Remove the pan from the heat and add the nutmeg, season with salt & pepper and stir. You now have a bechamel sauce.

Step 4

Still off heat, add the grated cheese and whisk until all the cheese melts into the sauce. It should be thick and smooth.

Step 5

Taste and adjust seasoning with salt & pepper and you now have Mornay sauce.