Step 1: Prepare the Spinach: Ensure the thawed spinach is thoroughly squeezed dry to remove excess moisture. This step is crucial for achieving the desired creamy consistency without a watery result. Place the spinach in a clean kitchen towel or cheesecloth and squeeze firmly.
Step 2: Create the Roux: In a large saucepan, melt the butter over medium heat. Whisk in the flour until a smooth paste forms, known as a roux. Cook for about 1-2 minutes, stirring constantly, until the roux is lightly golden. This step is essential for thickening the cream sauce.
Step 3: Develop the Cream Sauce: Gradually whisk in the heavy cream, ensuring no lumps form. Continue stirring until the sauce thickens slightly, about 3-5 minutes. Reduce the heat to low.
Step 4: Infuse Flavors: Stir in the nutmeg, garlic powder, salt, and pepper. Adjust the seasonings to taste, bearing in mind that the flavors will intensify as the sauce simmers.
Step 5: Incorporate the Spinach: Add the squeezed spinach to the cream sauce, stirring until well combined and heated through. Ensure the spinach is evenly distributed throughout the sauce.
Step 6: Add Cheese (Optional): If desired, stir in the grated Parmesan cheese until melted and incorporated. This adds a layer of savory richness to the dish.
Step 7: Serve Immediately: Serve hot as a side dish. Garnish with a sprinkle of nutmeg or Parmesan cheese, if desired.
For a richer flavor, consider using a combination of heavy cream and half-and-half. A pinch of cayenne pepper can add a subtle kick. To make ahead, prepare the dish up to the point of adding the spinach, then refrigerate. Reheat gently on the stovetop before serving, stirring in the spinach and cheese (if using) just before serving.