Preheat oven to 400° F.

• In a large roasting pan, drizzle the olive oil. Add onion, carrots, whole garlic cloves, and a pinch of Kosher salt. Toss until everything is coated with the olive oil.
• Place the squash halves, flesh side up, on top of the chopped vegetables. Sprinkle squash with some additional Kosher salt. Place roasting pan in the preheated oven and roast until the butternut squash is just tender, about 1 hour. It should be easy to pierce it with a fork or tip of a knife. Remove from oven and let the vegetables cool a little.
• When the butternut squash is cool enough to handle, scoop out the flesh and place it in a large stock pot with the other roasted vegetables. Add the chicken broth and maple syrup. Over high heat, bring the pot to a simmer. Reduce heat to low; simmer slowly about 45 to 60 minutes to allow the flavors to blend. Remove from heat.
• With an immersion blender, blend soup until very smooth. You can also use a stand blender by working in batches. After blending, pass the soup through a fine mesh sieve to remove any fibrous bits. If the soup seems like it's too thick, simply add a bit more water or chicken broth to bring it to the desired consistency.
• Stir in a pinch of Kosher salt to taste, and the cayenne pepper. Serve soup hot with a dollop of crème fraiche and some chopped fresh chives or rosemary. Sprinkle with a few pumpkin seeds.