Step 1: Preparation and Oven Preheat. Preheat your oven to a high temperature of 400°F (200°C). Line a large, sturdy, rimmed baking sheet with parchment paper or heavy-duty aluminum foil for easy cleanup. Thoroughly wash the Brussels sprouts, trim the hard stem end, and cut each sprout in half lengthwise. Quarter any particularly large sprouts.

Step 2: Initial Seasoning and Oil Coating. In a very large mixing bowl, combine the halved Brussels sprouts, 3 tablespoons of the olive oil (reserving the final tablespoon for the glaze), the kosher salt, black pepper, and minced garlic (if using). Use your hands to toss the sprouts vigorously until every piece is lightly and evenly coated with the oil and seasoning.

Step 3: Initial Roasting for Crispiness. Carefully pour the seasoned Brussels sprouts onto the prepared baking sheet. Spread the sprouts out into a single, even layer. Ensure they are not touching or overcrowded, as this will steam them. Place the pan into the preheated 400°F (200°C) oven and roast for 15 to 20 minutes. After the first 10 minutes, toss the sprouts with a spatula to encourage browning on all sides.

Step 4: Prepare the Balsamic Brown Sugar Glaze. While the Brussels sprouts are roasting, prepare the sweet glaze. In a small bowl, combine the remaining 1 tablespoon of olive oil, the packed light brown sugar, and the 3 tablespoons of balsamic vinegar. Whisk these ingredients together thoroughly until the brown sugar has mostly dissolved, creating a smooth, syrupy consistency.

Step 5: Glazing and Final Caramelization. After the sprouts have roasted for 15–20 minutes and the edges are starting to crisp up and turn golden brown, remove the baking sheet from the oven. Pour the prepared balsamic brown sugar glaze directly over the hot sprouts and toss gently to coat them evenly with the glaze.

Return the glazed Brussels sprouts to the 400°F (200°C) oven for an additional 5 to 10 minutes. Watch the sprouts closely during this final stage, as the high sugar content can burn easily. The goal is to allow the glaze to bubble, thicken, and deeply caramelize onto the sprouts, making them sticky and tender.

Step 6: Serve Immediately. Once the sprouts are tender and sticky-sweet, remove the pan from the oven. Transfer the Balsamic Brown Sugar Brussels Sprouts to a serving platter and scrape any remaining sticky glaze from the pan over the top. Serve the dish immediately while it is piping hot.