Grease the inside of your slow cooker with some of the butter, then add the corn, rest of the butter, cream cheese, milk or cream, and sugar. Season with salt and pepper as desired. Stir to mix.
Cover and set to Low setting for 4 to 6 hours (depending on how hot your slow cooker runs). At the 2 hour mark, give the corn a quick stir. At the 4 hour mark, stir again and taste, season with salt and pepper as desired, and if the corn is nice and tender, it is ready to serve, or set the cooker to Warm setting until ready to serve.
When ready to serve, stir the corn well, taste and season with salt and pepper as desired. If the corn is took thick, just stir in a little milk. Pour into a serving dish and garnish with parsley and or Parmesan cheese as desired.
Serve as a side with any main dish, and enjoy.