Add the uncooked pasta, milks, cheddar, mozzarella and American cheese, salt, pepper, garlic powder, ground mustard, paprika, cayenne pepper stir everything together.
Place the cubed butter pieces on top.
Cook on LOW for 2 hours (see notes) stirring after 1 hour. Or until pasta is done.
Season with more salt and pepper to taste.
Mac and cheese will thicken as it cools.
Notes
Shred your own cheese the bag cheese has a coating and doesn’t melt as smoothly.You want the American cheese from the deli counter.All slow cooker will cook differently. Mine is done after 2 hours but it may take up to an additional hour. Do NOT cook on high the cheese sauce can get gritty.Sany leftovers in an airtight container in the refrigerator for 3-4 days.