Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Trim the ends of the Brussels sprouts and cut them in half lengthwise.
Toss the sprouts on the baking sheet with 0.5 tbsp of olive oil, half of the sea salt, and half of the black pepper.
Roast the sprouts for 20-25 minutes, tossing halfway through, until they are tender and the edges are beautifully charred.
While the sprouts roast, season the chicken breast with garlic powder and the remaining salt and pepper.
Heat the remaining 0.5 tbsp of olive oil in a skillet over medium-high heat and sear the chicken for 6-7 minutes per side until fully cooked.
In a small bowl, whisk together the balsamic vinegar and maple syrup to create the glaze.
Once the sprouts are done, remove them from the oven and immediately toss them with the balsamic glaze and walnuts.
Slice the chicken breast into strips and serve alongside the warm, glazed Brussels sprouts.