For the chicken breasts: In a large saucepan, heat the extra-virgin olive oil and saute the onions for a minute, or until soft. Add the rosemary and chicken to the pan. Season the chicken with salt and pepper, and cook for a few minutes on each side, or until it is fully cooked and starts to brown. Finish cooking the chicken by adding the wine at the very end to deglaze the pan.
For the Zucca sauce: In a large saucepan, heat the extra-virgin olive oil and saute the onions for a minute, or until soft. Add the butternut squash, and cook for 5 minutes, or until tender. Add the vegetable stock, and salt and pepper, to taste, and let reduce. Stir in the gorgonzola cheese until it is fully melted in the sauce.
Transfer the chicken breasts to a warm plate, generously spooning the zucca sauce all over. Serve immediately.