In a large bowl, mix together the butternut squash and half the pesto until squash is well coated. Spread on a cookie sheet and cook for approximately 15 minutes.
While squash is roasting, wash Brussels sprouts and trim off ends. Cut each in half, or quarter if they are larger. Gently mix together sprouts with the rest of the pesto. Add sprouts to the pan of squash and roast for about 10 minutes.