Lightly grease a 6-quart slow cooker and add the uncooked pasta to it.
Scatter both the butter and cream cheese over the pasta.
Sprinkle the salt, pepper, cayenne, and paprika over the top and pour in the evaporated milk, whole milk and heavy cream. Stir to combine and try to make sure all the pasta is submerged.
Cover and cook on LOW for 1 to 2 hours (check after 1 hour), opening the slow cooker to stir halfway through.
Once the pasta is al dente (still a little chewy but mostly cooked), add the cheese and stir it in. Cover and cook for 10 more minutes.