Mashed potatoes are a requirement on most Thanksgiving tables, and we set a high bar. They must be lush and creamy with enough flavor to stand on their own, but not so assertive that they clash with the turkey gravy. I don't like to brag, but I think these are the potatoes you're looking for.
Even better, this casserole tastes best when made ahead, so you can get it done before the big day when many dishes are competing for precious oven space. Mashed potato casserole reheats beautifully, even in the microwave, which isn't true of most side dishes.