4 tablespoons unsalted butter
1 medium yellow onion, minced
3 cloves garlic, minced
4 teaspoons Kosher salt, divided
1 teaspoon freshly ground black pepper
1/2 teaspoon freshly grated nutmeg
1/4 cup all-purpose flour
3 1/2 cups half-and-half
2 1/4 pounds fresh leaf spinach (or one pound frozen)
1/2 cup grated Parmesan cheese
Optional, not found in the restaurant version
1 cup mozzarella cheese
4 ounces cream cheese

Bring a large pot of water to a boil with two teaspoons of salt.
Add the spinach and cook just until wilted, about 1 minute.
Drain the spinach in a strainer or colander.
Rinse with cold water until cool and squeeze the water out of each fistful of spinach.
Chop the spinach bundles into a 3/4 inch width.
In a large skillet melt the butter with the garlic and onions.
Cook on medium low for 8-10 minutes or until the onions are translucent.
Add in the remaining kosher salt, black pepper and nutmeg.
Add in the flour and mix with a wooden spoon over low and cook for 2-3 minutes until the aroma is a bit nutty.
Add the half an half and cook until boiling.
Add in the mozarella cheese and cream cheese
Cook for 6-8 minutes or until the mixture has thickened.
Add in the spinach and the Parmesan cheese and stir to combine.