Melt 3 Tablespoons of butter in a medium sauce pan over low heat.
Add the flour to make a roux, mixing together until blended.
Stir in half-and-half until incorporated.
Add the cream cheese and Parmesan and increase the heat to medium.
Continue to stir until melted and incorporated and then reduce heat.
In a large sauce pan saute the onions and garlic in remainder of butter (2 tablespoons) on medium heat until transparent.
Add the spinach by handfuls until all incorporated and cook until wilted but not soggy, about 5 minutes.
Add the salt, pepper and nutmeg to the cream mixture.
Add the spinach mixture to the cream and gently stir together.