Heat 2 tablespoons of olive oil over medium heat in a large, heavy pot or Dutch oven. Add the pancetta (or bacon) and cook over medium-low heat for 6 to 8 minutes, stirring occasionally, until lightly browned. Add the onions, carrots, celery, squash, garlic, and thyme and cook over medium heat, stirring occasionally, for 8 to 10 minutes, until the vegetables begin to soften. Add the tomatoes, 6 cups of the chicken stock, the bay leaf, 1 tablespoon salt, and 1 1/2 teaspoons pepper to the pot. Bring to a boil, then lower the heat and simmer uncovered for 30 minutes, until the vegetables are tender. Discard the bay leaf. Add the beans and cooked pasta and heat through. The soup should be quite thick but if it's too thick, add more chicken stock (I did not).