Preheat oven to 400°F and line a baking sheet with parchment paper.
Toss the butternut squash, carrots, red onion, tomato, garlic, and bell pepper with olive oil, sea salt, black pepper, and dried thyme.
Roast the vegetables for 25 minutes until they are tender and slightly caramelized.
While vegetables roast, poach the chicken breast in a small pot of simmering water until the internal temperature reaches 165°F, then shred with two forks.
Transfer the roasted vegetables to a high-speed blender along with the chicken broth and heavy whipping cream.
Blend on high until the mixture is completely smooth and velvety.
Pour the soup into a pot, stir in the shredded chicken, and heat through over medium-low heat before serving.