Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel and cube the butternut squash into 1-inch pieces and halve the Brussels sprouts, removing any yellowed outer leaves.
Cut the chicken breast into uniform 1-inch bite-sized chunks to ensure even cooking.
In a large mixing bowl, combine the chicken, squash, and sprouts, then drizzle with olive oil.
Sprinkle the dried thyme, ground cinnamon, sea salt, and black pepper over the mixture and toss thoroughly until every piece is well coated.
Spread the ingredients in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are fork-tender with golden edges.
While the bowl base roasts, thinly slice the half apple into matchsticks or wedges.
Divide the roasted chicken and vegetable mixture into serving bowls and top with the fresh apple slices for a bright, seasonal finish.