Preheat the oven to 400 degrees F. Line a rimmed sheet pan with parchment paper.
Place the butternut squash, baby carrots, garlic and onion in a large mixing bowl. Add the oil, salt and pepper and toss to coat.
Transfer the squash mixture to the lined sheet pan and spread the mixture evenly across the pan. Bake until the onions are lightly browned, 40 to 45 minutes. Allow to cool slightly.
Place half of the cooked vegetables in a blender using tongs along with 2 cups chicken broth and half the ginger. Blitz until smooth and transfer to a large soup pot. Repeat with the remaining vegetables, broth and ginger.
To serve immediately, place the pot over medium heat. Warm the soup through and season with salt and pepper to taste.
To freeze, divide soup evenly among four 16-ounce mason jars. Leave at least 1 inch of space at the top of each jar to prevent cracking. Screw on lids and freeze. To serve, place jars in a saucepan filled with cold water over medium heat until warm. Or, place a frozen jar in your lunchbox and reheat in the microwave for an on-the-go lunch.