Crock-Pot Mac & Cheese

Combine macaroni, butter, cheddar cheese, cream cheese, Parmesan, evaporated milk, whole milk, garlic powder, and paprika in a slow cooker. Season with salt and pepper. Cook on high until the pasta is cooked through and the sauce has thickened, 2 to 3 hours, checking after 2 hours, then every 20 minutes after. Garnish with chives before serving, if using.