Potato-Leek Soup

From J. Kenji Lopez-Alt/ Serious Eats

INGREDIENTS

2 tablespoons unsalted butter

2 large leeks, white and pale green parts only, rinsed and roughly chopped

1 quart homemade or store-bought low-sodium chicken stock

2 medium russet potatoes, peeled and cut into quarters (about 3/4 pound)

1 bay leaf

Kosher salt and freshly ground black pepper

1 cup buttermilk

1/2 cup heavy cream

1/2 teaspoon freshly ground nutmeg

Sliced chives or scallions, for serving

PREPARATION

Heat butter in a large saucepan or Dutch oven over medium heat until melted. Add leeks, reduce heat to low, and cook, stirring frequently, until very soft but not browned, 10 to 15 minutes.

Add stock, potatoes, and bay leaf, and season lightly with salt and pepper. Bring to a boil over high heat, reduce to a gentle simmer, cover, and cook until potatoes are fall-apart tender, about 15 minutes.

Add heavy cream and buttermilk to pot. Discard bay leaf. Blend soup until smooth with an immersion blender.(Working in batches if necessary, transfer soup to a blender. Slowly increase blender speed to high and blend until completely smooth, about 2 minutes.) (Return soup to a clean pot, pressing it through a fine-mesh strainer with the bottom of a ladle if a smoother texture is desired.) Whisking frequently, bring soup to a simmer over medium-high heat. Alternatively, chill completely and serve cold. Whisk in grated nutmeg. Season to taste with salt and pepper and serve with chives or scallions.