Boil the macaroni according for 6 minutes. Drain it and set aside.
In a medium saucepan, combine the butter and cheese and stir until the cheese melts. Let the mixture cool for several minutes.
Transfer the mixture into a slow cooker and gradually beat in the eggs.
Add the sour cream, soup, salt, milk, mustard, pepper, and drained macaroni. Stir to combine.
Cook on low heat for 2 ½ hours, stirring occasionally to prevent the mac and cheese from sticking to the bottom.
Serve and enjoy!
