Place washed spinach in a bowl with salted water about 10 minutes; strain well. In a large skillet add Secolari Arbosana Olive Oil and spinach and cook for a few minutes until the spinach is free of liquid. Keep warm.
Add the onion to another pan with 1 cup of water, white wine, Secolari Fleur de Sel Sea Salt, pepper and nutmeg. Add and mix 2 tablespoons of the cold water in a small bowl with the flour. Add to the pan and cook for 10-15 minutes until the onions are done. Taste for seasoning.
Place spinach on a deep plate or platter. Add the sauce on top and top with grated Parmesan.