Yes, you can easily prepare baked mac and cheese ahead of time. Just assemble it according to the recipe, but do not bake it yet. Let the assembled dish cool, then cover it with foil and refrigerate it for up to two days. When you are ready to bake, take the dish out and let it sit for 30 minutes to reach room temperature, then bake until it is piping hot and bubbly. Keep in mind, if you make it ahead, the mac and cheese might be a bit less creamy. To avoid this, simply add a little more sauce before you refrigerate it. This will help keep your mac and cheese deliciously creamy when you serve it.