I love the earthy flavor of buttercup squash, but you can substitute butternut or another one of my favorites, Red Kuri squash. Note: The herb butter recipe below makes enough for both this soup (designed to serve 12 in Michael Brisson’s Thanksgiving Feast menu) and for rubbing the turkey in the accompanying recipe.
Makes 12 cups
For the herb butter:
• 1 shallot, finely chopped (about 2 tablespoons)
• 1/2 cup dry sherry
• 1/2 pound (16 tablespoons) unsalted butter, at room temperature
• 2 tablespoons chopped fresh chives
• 1 teaspoon kosher salt
• 1/4 teaspoon white pepper
For the soup:
• 4 cups chopped, well-washed leeks, white part only (about 4 to 5 large)
• 8 cups peeled, seeded, and diced (1-inch cubes) buttercup squash (about 3 medium)
• 1/2 cup dry white wine
• 6 cups homemade or low-salt chicken broth
• 1 ½ to 2 tablespoons kosher salt
• ½ to 1 teaspoon white pepper
• Chopped fresh chives for garnish
Up to two weeks ahead: Make the herb butter
1. Heat a small nonstick sauté pan over medium heat. When hot, add the shallots and heat to release their aroma and lightly toast them, about 30 seconds. Remove from the heat and add the sherry.
2. Set the pan back on the heat and reduce the liquid to 2 tablespoons, about 8 minutes. Let cool. In a small mixing bowl, blend the butter, chives, sherry-shallot mixture, salt, and pepper.
3. Line a baking sheet with parchment or waxed paper and spread the butter 1/4 inch thick to cover about 8×6 inches. Cover and chill. With a small cookie cutter (I use a star) or a knife, cut out 12 small shapes. Wrap in plastic and freeze; freeze the remainder separately for the turkey.
Up to three days ahead: Make the soup
1. Put the leeks in a heavy-based nonaluminum, 8 quart soup pot. Put the squash over the leeks; add the wine and broth. Cover and bring to a boil. Reduce to a simmer; cook until the squash is fork-tender, about 25 minutes. Let cool 15 minutes.
2. Add 1 tablespoon salt and ½ teaspoon pepper; purée in batches in a blender (taking care not to fill the blender more than two-thirds full) or directly in the soup pot with an immersion blender. Taste and season with more salt and pepper if needed. Refrigerate up to three days.
On the day of serving:
1. Defrost the butter shapes. Reheat the soup over low to medium heat, stirring frequently.
2. To serve, ladle the hot soup into shallow bowls and garnish with herb butter and fresh chives.
