Preheat oven to 425°F (220°C). Line a large, rimmed baking sheet with parchment paper or foil for easier cleanup.

In a large mixing bowl, toss the trimmed Brussels sprouts with 3 tablespoons of olive oil, kosher salt, black pepper, and garlic powder until they are evenly coated.

Transfer the seasoned Brussels sprouts to the prepared baking sheet. Ensure they are spread out in a single layer, preferably cut-side down, to maximize crisping. Avoid overcrowding the pan, as this will cause steaming.

Roast for 15 minutes. Remove the pan from the oven, shake it gently to flip the sprouts, and return to the oven. Continue roasting for an additional 5 to 10 minutes, or until deeply charred and tender.

While the Brussels sprouts are finishing cooking, prepare the glaze. In a small saucepan, combine the balsamic vinegar, honey (or maple syrup), and water (if using).

Heat the mixture over medium heat. Bring to a gentle simmer, then reduce heat to medium-low. Allow it to bubble and reduce for 3 to 5 minutes, stirring occasionally, until it slightly thickens to a syrupy consistency. Remove from heat immediately.

Remove the crispy Brussels sprouts from the oven. Transfer the hot sprouts to a clean large mixing bowl. Pour the warm honey balsamic glaze over the roasted sprouts and toss quickly but gently until all are coated.

Serve immediately while hot and crispy. Garnish with a sprinkle of flaky salt or sesame seeds if desired.