Make the Nutmeg Spinach Sauce.
Soften butter in medium saucepan over medium warmth. Stir in onion, cowl, and cook dinner, stirring incessantly, till comfortable and aromatic however not browning, 10 minutes or so. Stir in garlic, nutmeg, salt, and pepper and proceed cooking for a minute. Add water and spinach and cook dinner, stirring always, simply till brilliant inexperienced and wilted, solely a minute or two. Switch to high-speed blender and punctiliously purée till clean. (Scorching liquids are harmful—they’ll violently erupt. For security, drape kitchen towel over blender, begin slowly, then progressively improve pace.) Return sauce to pot and reserve at room temperature. Deliver to simmer simply earlier than serving.