Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Toss the cubed butternut squash with olive oil, sea salt, and black pepper until evenly coated.
Spread the squash in a single layer and roast for 25-30 minutes until the edges are golden and caramelized.
While the squash roasts, sauté the diced yellow onion in a large pot over medium heat until translucent.
Add the minced garlic to the pot and cook for 1 minute until fragrant.
Transfer the roasted squash to the pot and pour in the chicken bone broth.
Bring the mixture to a gentle simmer for 5 minutes to meld the flavors.
Use an immersion blender to process the soup until it reaches a velvety, smooth consistency.
Stir in the ground nutmeg and fresh thyme, then fold in the shredded chicken breast to heat through.
Serve hot in bowls, garnished with extra thyme if desired.