Directions

1. Melt butter in a medium saucepan over medium heat. Add leeks, and cook, stirring occasionally, 5 minutes. Add potato, 1/8 teaspoon pepper, and the nutmeg, and cook, stirring, 1 minute. Stir in cauliflower, 1/4 teaspoon salt, and 3 cups stock. Simmer, partially covered, until cauliflower has softened, 12 to 15 minutes. Using a slotted spoon, remove 2 florets, and transfer to a cutting board; thinly slice lengthwise. Set aside for garnish.
2. Working in batches, puree vegetable mixture in a blender, filling no more than halfway each time. Return to pan. Stir in buttermilk and remaining 1/2 cup stock. Sprinkle with 1/2 teaspoon salt, and season with pepper. Serve hot or cold, garnished with cauliflower slices.