In the basin of a 5 or 6-quart slow cooker, combine the frozen corn, cubed butter, heavy cream, whole milk, sugar, salt, pepper, and nutmeg (if using). Stir everything together to combine.

Place the cubes of cream cheese evenly on top of the corn mixture. Do not stir it in yet; it will melt down into the corn as it cooks.

Cover the slow cooker and cook on LOW for 3-4 hours or on HIGH for 2-2.5 hours, until the mixture is hot and bubbly around the edges and the cream cheese is very soft.

Remove the lid and stir vigorously with a whisk or large spoon to fully incorporate the melted cream cheese and butter. Continue stirring until the mixture is creamy and smooth.

Thicken (Optional): If you prefer a thicker creamed corn, create a slurry. In a small bowl, whisk together the cornstarch and cold water until no lumps remain. Pour the slurry into the slow cooker and stir until well combined. Cover and cook on HIGH for another 15-20 minutes, or until the corn has thickened to your liking.

Taste and adjust seasoning with more salt and pepper if needed. Transfer to a serving dish and garnish with fresh chives before serving warm.