In a sauté pan on medium high heat melt the butter and add the shallots, salt, pepper, and nutmeg. Cook until they are translucent and add the spinach a handful at a time. Cook until they wilt before adding the next batch.
Continue this process adding the garlic once half of the spinach has been added to the pan.
Once all of the spinach has been wilted, add the cream cheese and cook until it is melted. Add the half and half and heavy cream and bring to a boil. Stir to keep the milk from scalding. Keep cooking until the milk reduced by half, remove from the heat and add the parmesan cheese stirring to combine until all of the cheese has melted.