Preheat an oven to 425°F (220°C).

In a roasting pan, combine the squash, carrots, onions, garlic, thyme, basil and parsley. Season with 1 tsp. salt and a grinding of pepper. Drizzle the 1/4 cup olive oil over the vegetables and toss to coat. Roast, stirring every 15 minutes, until tender and browned in spots, about 45 minutes.

Remove the vegetables from the oven and discard the thyme sprigs. Transfer the vegetables to a soup pot and add 4 cups of the broth. Using an immersion blender, puree the soup until smooth. Alternately, transfer the soup to a blender, puree until smooth and return the soup to the pot. Add more broth to thin the soup to the desired consistency. Place over medium-low heat and cook until warmed through, about 10 minutes.

Meanwhile, in a dry fry pan over medium-low heat, sauté the pancetta until crisped and some of the fat is rendered, 12 to 15 minutes. Transfer to paper towels to drain.