3 or 4 ( 1/2 -inch) slices French country white bread
1 teaspoon salt
1/8 teaspoon white pepper
3/8 cup sour cream
3/4 teaspoon ground piment d'espelette for garnish
3 teaspoons chopped parsley for garnish
1. Heat the oven to 400 degrees. Place the garlic in a small bowl with the olive oil and set aside.
2. Heat 2 tablespoons of the butter in a large sauce pot until melted. Add the celery, carrots and onion and sauté over medium-low heat until tender, about 10 minutes, stirring occasionally. Add the minced garlic and sauté until fragrant, about 1 minute.
3. Add the squash to the pot. Stir in the chicken broth and bring the mixture to a boil. Reduce the heat and simmer 45 minutes to 1 hour, until the squash is tender.
4. While the soup simmers, make croutons by cutting the bread slices into 12 (half-inch by 4-inches) strips. Brush the cut sides of the bread with the garlic-infused oil. Place on a baking sheet and bake 12 to 15 minutes, until lightly browned. Set aside.
5. When the squash is tender, purée the soup in a blender or food processor, in batches if necessary. Return the soup to the pot. Add the remaining butter, bit by bit, to the soup, swirling until each piece is incorporated and the soup is slightly thickened. Season with salt and pepper.
6. To serve, spoon about three-fourths cup soup into each of 6 soup bowls. Top each with a dollop of sour cream and a pinch of piment d'espelette. Sprinkle parsley over the croutons, then place 2 croutons on top. Serve immediately.