0: Now it's time for that cheese sauce! In a medium sized pan over medium heat,
add butter and let it melt. When it's melted add the flour in order to make the
roux, the roux is going to help thicken the sauce.
Stir the roux for about two minutes and then add in the milk.
Continue stirring the milk until it starts to simmer and thicken.
It should take about four minutes next at the creme fraiche and continue to
stir to incorporate. Once it's combined it should have a nice thick texture.
So go ahead and turn off the heat and then finish by adding the cheddar cheese
mustard, salt, and pepper, and stir until it's melted in combined.