1. Make the soup: Cut a round of parchment to fit inside a large pot. Melt butter in pot over medium heat. Add leeks and a pinch of salt, and cover with parchment round (this will help keep moisture in). Cook, lifting parchment to stir occasionally, until leeks are tender, 10 to 15 minutes.

2. Stir in parsnips, potatoes, chicken stock, 2 1/2 cups water, bay leaves, and 1 teaspoon salt. Raise heat to high, and bring to a boil. Reduce heat to medium-low. Simmer gently, partially covered with lid, until parsnips are soft, about 20 minutes. Discard bay leaves. Let cool slightly, about 10 minutes.

3. Working in batches, puree vegetable mixture in a blender, being sure to hold lid down.

4. Return soup to pot, and stir in milk. Reheat soup over medium heat (do not boil).

5. Make the black-pepper cream: Stir 1/4 teaspoon pepper into creme fraiche.

6. Ladle soup into 8 small bowls, and top each with a dollop of black-pepper cream and 1/2 teaspoon caviar.