After rinsing the spinach, leave some water clinging to the leaves. This will help the spinach wilt evenly in the pan, without becoming too soft. Try serving with Pork Chops with Apples and Shallots.
In a large, deep saucepan with a tight-fitting lid, melt butter over medium heat. Add spinach (with water still clinging to leaves); cover, and cook until wilted, stirring halfway through, about 5 minutes.
Remove from heat. Season with nutmeg, salt, and pepper. Serve immediately with a slotted spoon.