Here, you can use chard, kale, or spinach to make an easy, delicious side dish. Coarsely chop the greens (with any tender stems), steam them until cooked through, then squeeze them dry in cheesecloth or a clean kitchen towel.
Melt butter in a medium saucepan over medium-high heat. Add shallot and cook, stirring, until softened, about 3 minutes. Add flour and cook, stirring, 1 minute.
Add milk, whisking until mixture just comes to a simmer. Gently simmer, stirring constantly, until mixture is thickened, about 5 minutes. Stir in greens, nutmeg, salt, and pepper and cook until heated through. Creamed greens can be made 1 day ahead, cooled completely, and stored in refrigerator. Reheat, stirring, over medium heat.