Leeks are easy to grow, but they do require a long growing season. Fortunately, you can harvest them into late fall and some varieties actually taste better once they've been nipped by frost. Most leek and potato soups look bland, but my version gets a colorful lift with the addition of spinach leaves. Enjoy!
Heat the butter in a large pot over medium-high heat. Add the leeks and garlic and cook, stirring often, until the leeks are tender, about 15 minutes. Add the potatoes and celeriac and cook, stirring often, to blend the flavors, about 5 minutes. Add the broth, nutmeg, and bay leaf and bring to a simmer over high heat. Return the heat to medium-low and cover. Simmer until the potatoes are tender, about 30 minutes. Remove the bay leaf.
In batches, puree the soup in a blender or food processor until smooth. Add the spinach leaves and pulse to blend. If serving hot, return to the pot, season with salt and pepper, and gently reheat. If serving cold, transfer to a bowl and cool. Cover and refrigerate until chilled, at least 2 hours. Season with salt and pepper shortly before serving. Serves 6 to 8.
Recipe by Ellen Ecker Ogden from her book From the Cook's Garden (HarperCollins, 2003). Ellen is a garden writer and cookbook author based in Vermont.