Preheat your oven to 400º.  Cut off and discard the ends of the butternut squash.  Peel the squash, cut it in half lengthwise, and remove the seeds.  Cut the squash into 1 1/2 inch cubes and place them in a large bowl.  Pour the melted butter, brown sugar, salt, pepper and thyme leaves over the squash and toss all the ingredients together.  Spread on a baking sheet lined with parchment paper.  Roast for 45 – 55 minutes, until the squash is tender and the glaze begins to caramelize.  Toss a few times with a  spatula during cooking.  You can also substitute maple syrup the brown sugar if you wish!