Preheat the oven to 350 degrees F (175 degrees C). Lightly grease a 2-quart baking dish.
Boil macaroni in a large pot of salted water until barely done, about 5 minutes. Drain and set aside to cool slightly.
Whisk milk and egg together in a large bowl; stir in cheese and butter.
Place par-boiled macaroni in the prepared baking dish. Pour milk mixture over macaroni, season with salt and pepper, and stir until combined. Press mixture evenly into the baking dish.
Bake, uncovered, in the preheated oven until top is golden brown, 30 to 40 minutes.
Serve hot and enjoy!
Tips
Changes I made were I added 4 cups of mozzarella and cheddar (2cups of each) and baked it for 50 minutes (covered the first 20) I also stirred it a couple times
