Preheat the oven to 400°F and line a large rimmed baking sheet with parchment paper.
Place the halved brussels sprouts and diced chicken breast on the sheet, then drizzle with olive oil, sea salt, and black pepper.
Toss the ingredients until evenly coated and spread them out in a single layer to ensure they roast properly without steaming.
Roast for 15 minutes, then remove the tray and scatter the torn prosciutto pieces over the chicken and sprouts.
Return the tray to the oven for 5 to 8 minutes until the prosciutto is perfectly crispy and the chicken is cooked through.
Whisk the balsamic vinegar and honey in a small bowl until well combined.
Drizzle the balsamic glaze over the pan, toss gently to coat, and roast for a final 2 minutes until the sauce is sticky and caramelized.
Finish the dish by garnishing with fresh thyme leaves for a bright, herbal aroma before serving.