Add 1 teaspoon of salt to a large pot of water and bring to a boil.
Add the spinach to the water and cook about 1 minute until wilted.
Drain the spinach and rinse with cold water until cooled.
Squeeze out water and chop into strips. Set aside.
In a large pan, melt butter over medium low heat,
Add diced onion and garlic and cook about 10 minutes until translucent.
Add in the remaining salt, pepper and nutmeg.
Add in the flour and stir to form a roux.
Cook over low heat for another 3 minutes.
Stir in the half an half and cook until mixture starts boiling.
Stir in the grated parmesan cheese
Cook until thickened, about 8 minutes.
Add the spinach and stir to combine.
Cook for just a minute or 2 to warm up spinach.