Peel the butternut squash, then chop off the neck. Cut the neck into rounds, then dice into 1" pieces. For the bottom part, cut in half and scoop out the seeds. Set the seeds aside and chop into 1" pieces. Place squash on a baking sheet.
In a small bowl, whisk together the oil, syrup, cinnamon and salt together. Drizzle over the squash and stir to coat.
Roast on the center rack for 2o minutes, stirring halfway through.
Remove after 20 minutes and stir in pecans and rosemary. Place back in the oven for another 10 minutes or until the squash is fully cooked through.
Let cool for 5 minutes, then transfer to a dish and serve immediately!*
* This dish can also be made ahead and reheated in an oven safe dish at 300ºF.