Preheat the oven to 325 degrees F. Place the melted butter in a 9×13 baking dish. (I like to melt the butter in the pan as the oven is preheating. Just watch so it doesn’t burn. I set the timer for 3 minutes so I don’t forget.)
Toss the uncooked noodles in the melted butter.
Evenly cover the noodles with the shredded cheese, pour the milk over all, and sprinkle with the salt and pepper.
Bake, uncovered, for 1 hour. After 30 minutes, remove from the oven and carefully stir for about 2 minutes or until the cheese completely dissolves into the milk. Return to the oven for the final 30 minutes of baking.
If you’d like to create a little extra golden brown color and crisp bits on top, broil the mac and cheese on the top rack of the oven, watching very carefully to avoid burning, during the final 2-3 minutes of the baking time. Remove from the oven and allow the casserole to sit for a few minutes before serving.