- Preheat your oven to 400 F. 
- Prepare the butternut squash by cutting it in half, removing the seeds and peeling it with a knife. Now cut the peeled squash into cubes. - 1 medium butternut squash 
- Combine the rosemary, 1 tablespoon balsamic vinegar, garlic and olive oil in a bowl and season to taste with sea salt and freshly ground black pepper. - 2 tablespoon extra-virgin olive oil, 1 clove garlic, 1 tablespoon + 1 teaspoon balsamic vinegar, 1 teaspoon fresh rosemary leaves, Sea salt and freshly ground black pepper to taste 
- Toss the butternut squash cubes in the liquid and place in a baking dish. 
- Place in the preheated oven for about 40 minutes, until soft and caramelized. 
- Remove from the oven, toss the cooked squash with the remaining 1 teaspoon balsamic vinegar and serve.