Drain macaroni and return to cooking pot.Once it is at the thickness you desire remove from heat immediately and add cheese, reserving about a 1/4 of a cup of cheddar. When the mixture begins to boil you will notice your sauce will start to thicken. Salt and pepper your sauce to your liking.
Once you get your rue to the color you want add the milk while continuing to whisk constantly.You want your rue to be almost a copper brown color.
If rue burns throw it out and start again.