Preheat the oven to 180°C.
Cut the onion into thin wedges and chop the garlic.
Cut the runner beans into 3 cm chunks.
Scatter the runner beans into a small roasting dish, then put a few basil leaves on top.
Put the chicken breast on top of the basil leaves, then arrange the onion wedges and tomatoes around the chicken.
Scatter the garlic over the dish, then season with salt & pepper, drizzle with oil and balsamic vinegar.
Cover the dish with foil and bake for about 20 minutes, until the chicken is tender.
Remove the foil, then add some grated cheese and bake for a further 2-5 minutes, until the cheese has just melted.
Serve with basil leaves scattered on top, then drizzle with balsamic glaze.