3 pounds spinach
4 tablespoons butter
2 tablespoons flour
1 cup milk
2 tablespoons heavy cream
1/4 teaspoon freshly grated nutmeg
1 teaspoon kosher salt
1/8 teaspoon freshly ground black pepper

1. Remove the stems from the spinach leaves. Discard any leaves that are discolored or tough. Soak the spinach in a large bowl of cold water, stirring
to dislodge sand and grit. Change the water at least two or three times to ensure that the spinach is absolutely clean. (With each change of water, lift the spinach out of the bowl with your hands rather than draining the water into a colander. That way you won’t pour the sandy water back onto the spinach.) Thoroughly dry the spinach in a salad spinner or on paper towels.
2. To make the béchamel, melt 2 tablespoons of the butter in a non-reactive saucepan over low heat. Sift in the flour and stir with a wooden spoon until the flour is completely incorporated into the butter. Cook gently, stirring,
for 5 minutes. Don’t let the flour brown. Remove the roux from the heat
and whisk in the milk. Return to a boil, whisking constantly, and cook 2
to 3 minutes longer. Cover and set aside while you cook the spinach.
3. In a large skillet, melt 1 tablespoon butter. Cook the spinach, stirring until wilted, and simmer 1 minute longer if necessary to remove any excess
water from the spinach.
4. Pulse the cooked spinach in a food processor to make a coarse purée.
5. Add the puréed spinach to the saucepan with the béchamel. Bring to a simmer and stir in the heavy cream, nutmeg, salt, pepper, and remaining butter. Serves 4.