Melt the butter in a large skillet over medium heat and add the minced garlic, cooking for about 1 minute until fragrant.
Add the fresh spinach in batches, stirring until wilted down, about 3-4 minutes total.
Reduce heat to low and add the cream cheese, heavy cream, and nutmeg, stirring until the cream cheese is fully melted and the sauce is smooth.
Stir in the Parmesan cheese and season with salt and pepper to taste.
Cook for an additional 2-3 minutes until the sauce has thickened slightly, then serve warm.