Why did my mac and cheese turn grainy?
Most of the time it is heat. Keep the sauce at a gentle simmer, not a boil, and turn the heat to low (or even off) before adding cheese. Also, shred your own cheese if you can. Pre-shredded cheese often has anti-caking agents that make sauces less smooth. One more thing: super aged cheddar can get a little oily or grainy in sauces, so save the really fancy stuff for a cheese board.
How do I keep baked mac and cheese from drying out?
Make the sauce slightly looser than you think you need. It thickens in the oven and again as it cools. Also, do not overbake. You are baking to set the top and marry flavors, not to reduce the sauce into paste.
Can I make this on the stovetop only?
Yes. Skip the topping, and after you mix pasta and sauce, let it sit 3 to 5 minutes to thicken. If you want a little crunch, toast breadcrumbs in butter in a skillet and sprinkle on top.
What pasta shape works best?
Elbows are classic, but cavatappi is my favorite for this. The spirals trap sauce like it owes them money.
Can I add protein?
Absolutely. Stir in cooked bacon, shredded chicken, or browned sausage right before baking. If it is salty, pull back a little on the added salt in the sauce.
Can I make it ahead?
Yes, and it is a weeknight lifesaver. Assemble, cover, and refrigerate up to 24 hours. Bake covered at 375°F for 20 minutes, then uncover and bake 10 to 15 minutes more until bubbling and golden. If it looks tight, stir in a small splash of warm milk before baking.