Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Trim the ends of the Brussels sprouts and slice them in half vertically.
In a bowl, toss the sprouts with half of the olive oil, half of the sea salt, and half of the black pepper.
Spread the sprouts on the baking sheet in a single layer and roast for 18-20 minutes until the outer leaves are crispy and golden.
While the sprouts roast, cut the chicken breast into bite-sized cubes and season with garlic powder and the remaining salt and pepper.
Heat the remaining olive oil in a non-stick skillet over medium-high heat and sauté the chicken until browned and cooked through, about 6-8 minutes.
In a small ramekin, whisk together the balsamic vinegar and maple syrup to create the glaze.
Add the roasted sprouts and chopped walnuts to the skillet with the chicken, then pour the balsamic glaze over the top.
Toss everything together for 1-2 minutes until the glaze has thickened and coated the ingredients beautifully.