Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Trim the ends off the Brussels sprouts and slice them in half; cut the chicken breast into uniform 1-inch bite-sized pieces.
In a large mixing bowl, toss the chicken and Brussels sprouts with the extra virgin olive oil, sea salt, black pepper, and garlic powder until evenly coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the sprouts are cut-side down for maximum caramelization.
Roast in the oven for 20 to 25 minutes, tossing halfway through, until the chicken is cooked through and the sprouts are golden and crispy.
While the tray is roasting, add the balsamic vinegar and honey to a small saucepan over medium-low heat.
Simmer the balsamic mixture for 5 to 7 minutes until it reduces by half and becomes a thick, syrupy glaze.
Remove the tray from the oven, transfer the chicken and sprouts to a plate, and drizzle the warm balsamic glaze over the top before serving.