Heat the olive oil in a large pot over medium heat. Add the onion and generous pinches of salt and pepper and cook, stirring occasionally, until soft and lightly browned about 5-8 minutes.Add the butternut squash and celery and stir.Add the mushrooms, another pinch of salt and a few grinds of pepper, and cook until soft, about 8-10 minutes.Add the garlic, bay leaves, sage and Herbes de Provence. Stir, then add the wine and stir again. Add the vegetable broth, tomatoes, beans and bundled thyme sprigs. Simmer for 30 minutes, until thickened, stirring occasionally. Remove the thyme stems and bay leaves.Add the balsamic vinegar. Stir in the chopped kale and cook until wilted, about 5 minutes. Taste and adjust seasonings.Serve with pecorino cheese and toasted baguette if desired.