Preheat oven to 425°F. Place brussels sprouts, bacon and garlic on a large rimmed baking sheet, lined with parchment paper. Season with salt and pepper. Drizzle with olive oil and toss until well combined.
Bake until sprouts are tender and charred, about 30 minutes.
Meanwhile, in a small saucepan, combine balsamic vinegar, honey and rosemary. Simmer, stirring occasionally, until reduced by half for about 15 minutes. When ready, the mixture should coat the back of a spoon.
When brussels spouts are done, drizzle evenly with balsamic glaze. Serve immediately.