I have promised to prepare several dishes ahead of time for Thanksgiving this year and most of them are well-documented on how to prepare ahead of time: bread rolls, mashed potatoes, etc. However, one item I committed to making doesn't seem to have a lot of resources dedicated to prepping ahead: mac and cheese. Some recipes exist but I do not have extreme confidence considering my prior experience with roux-based sauces.
I am planning on using this mac and cheese recipe. When the sauce & cheese are not heated to the correct temperature and then immediately put in the oven, the sauce usually comes out grainy. (Previous failed attempts resulting in grainy sauce may be the result of overheating but I have not confirmed that.) How can I go about preparing this recipe ahead of time so that it can simply be put in the oven to heat prior to serving? Since the final step is to bake it, should I just refrain from baking and instead delay until it is ready to serve? Or should I partially bake it and finish the baking later? Additionally, is there an ideal temperature the roux should be at the avoid the grainy texture?