Spray the inside of your slow-cooker with cooking spray or grease it with olive oil. Combine milk, evaporated milk, eggs, butter, and salt in slow-cooker and whisk until until smooth (or you can use an immersion blender to do the whisking for you).

Add the shredded cheese (not the Parmesan) and macaroni, sprinkle with black pepper (and whatever other spices you want to use). Stir gently with a spatula to coat evenly.

Sprinkle the Parmesan cheese on top. Cover and cook on HIGH for 30 minutes.
After 30 minutes, reduce the temperature to LOW and cook for 2 to 2 1/2 hours, until custard is set in the center and the pasta is tender. The macaroni and cheese may sit in the cooker on the KEEP WARM setting for 30 minutes before serving. Before dishing it up, I sautéed some bread crumbs with olive oil and sprinkled them over the top to make it a little fancier.