01 - Heat butter in large skillet over medium heat. Add chopped onion and cook 2-3 minutes until translucent.
02 - Stir in minced garlic and cook 1 minute until fragrant.
03 - Add spinach in batches, stirring until wilted and most moisture evaporates, approximately 5 minutes.
04 - Pour in heavy cream and sprinkle nutmeg, salt, and pepper. Stir to combine and bring to gentle simmer.
05 - Stir in Parmesan cheese until melted and sauce reaches creamy consistency.
06 - Using spoon, create four wells in spinach mixture. Crack one egg into each well.
07 - Cover skillet and cook 6-8 minutes until whites are set and yolks remain slightly runny. Extend cooking time for firmer yolks if preferred.
08 - Remove from heat and serve immediately. Garnish with additional Parmesan if desired.