Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Prepare the Brussels sprouts by trimming the woody ends and slicing each sprout in half lengthwise.
Cut the chicken breast into uniform 1-inch cubes to ensure even cooking.
In a large mixing bowl, combine the halved Brussels sprouts and chicken cubes.
Drizzle with olive oil and sprinkle with sea salt, black pepper, and garlic powder, tossing thoroughly to coat every piece.
Spread the mixture onto the prepared baking sheet in a single layer, ensuring they aren't overcrowded so they roast rather than steam.
Roast in the oven for 20 to 25 minutes, tossing halfway through, until the chicken is cooked through and the sprouts are charred and tender.
Remove from the oven, transfer to a serving plate, and drizzle the balsamic glaze over the top while still hot.