Preheat the oven to 200°C/400°F/gas 6. Put 1 chicken breast, with its skin left on, in a bowl. Add 8 trimmed sticks of asparagus, 6 halved cherry tomatoes and the leaves from 1 sprig of fresh rosemary plus a whole sprig of rosemary as well. Toss everything together with a pinch of sea salt and freshly ground black pepper and a drizzle of olive oil. Put the veg into a tinfoil tray and place the chicken and rosemary sprig on top. Season well. Add some white wine and cook in the middle of the oven for 25 to 35 minutes. Serve drizzled with balsamic vinegar.