Step 1: Cook the Aromatics
In a large skillet over medium heat, melt the butter. Add the chopped shallots and cook for about 3–4 minutes until softened. Stir in the minced garlic and cook for another 30 seconds until fragrant.
Step 2: Make the Cream Sauce
Pour in the heavy cream and bring to a gentle simmer. Season with salt, black pepper, and a pinch of nutmeg. Let the sauce cook for about 5 minutes, stirring occasionally, until it begins to thicken slightly.
Step 3: Add the Cheese
Stir in the grated Parmigiano-Reggiano cheese and mix until fully melted and the sauce becomes smooth and creamy.
Step 4: Add the Spinach
Add the thawed and well-drained spinach to the skillet. Stir thoroughly to coat the spinach in the creamy sauce.
Step 5: Simmer and Serve
Cook for another 3–5 minutes until everything is heated through and well combined. Taste and adjust seasoning if needed. Serve warm as a rich and flavorful side dish.