Heat the olive oil in a large skillet over medium heat. Add the onions and garlic cook for about 4-5 minutes until soft.
Stir in the heavy cream, salt, pepper, and nutmeg. Bring to a boil over medium heat, then reduce to a gentle simmer. Cook for 8-10 minutes until the mixture is thick enough to coat the back of a spoon.
Add the spinach and mix until evenly coated. If the spinach releases too much water, just keep cooking it until the mixture thickens. Stir in the Parmesan cheese. Serve immediately.
Nutrition information is calculated using an ingredient database and should be considered an estimate.