Special equipment: an immersion blender
Preheat the oven to 400 degrees F.
Toss the squash with the 1/4 cup olive oil, 1/2 teaspoon salt and 1/4 teaspoon pepper in a 9-by-13-inch roasting pan. Arrange the squash in a single layer and add the thyme. Roast until the squash is tender when pierced with a knife, about 30 minutes.
Warm the remaining 2 tablespoons olive oil in a large pot over medium heat. Add the garlic, onion and pancetta; saute, stirring occasionally, until the onion has softened and the pancetta is lightly browned, 5 to 7 minutes. Add the roasted squash and the wine, and bring to a simmer. Allow the wine to reduce until almost dry, about 5 minutes. Add the vegetable stock, peppercorns and bay leaf. Cover and cook on low heat for 20 to 25 minutes. Remove from the heat and discard the bay leaf, pancetta, thyme, and peppercorns (usually are not too hard to find since they're black in a mostly orange pot!). Puree the soup with an immersion blender or in batches in a blender. If you find the soup too thick, add some water, a little at a time. Season with salt and pepper. Serve piping hot with a dollop of creme fraiche or sour cream and some fresh bread.