Blend all ingredients in a blender for 30 seconds to 1 minute, until smooth. Add more water as needed. Enjoy!
To roast the squash, spread out diced butternut squash on a baking sheet lined with parchment paper, and roast at 400 degrees F for 20-25 minutes. Roasted squash will keep in an airtight container in the fridge for a few days.
If you are using raw or frozen squash and have an old blender that's not that powerful, you may want to lightly steam it before blending.
If you do not have a frozen banana, add some ice cubes to make the smoothie colder.