Spray the pot of the slow cooker or if using a liner bag, spray the bag well. In a mixing bowl whisk together milk, evaporated milk, egg, salt and pepper. Pour milk mixture into the crockpot. Add cheese and uncooked macaroni. Stir gently to mix. Turn slow cooker on low and cook 3-4 hours, or until the cheese is set and the macaroni is tender. (Do not cook more than 4 hours, or the sides will begin to dry out). Serve at once. Tips: between the 3-4 hour mark on low, the edges start to get that crispy, cheesy edge. Kids love that part, but if yours don't you'll want to make this when you know you can cut it to warm or serve it at about the three hour mark.
EDITED TO ADD: I added 1 tsp of dry mustard.
It turned out incredible! It was so creamy and cheesy. I have learned that after 30 years old box mac and cheese just doesn't cut it anymore. I know, I'm so grown up. But this recipe? It totally cuts it. I bet if you add a little bacon and breadcrumbs on top it would make this even more grown up and knock your socks off. I just might have to do that the next time I make this. Because there will be a next time!