Preheat the oven to 190C / 375F / gas mark 5.
Trim the chicken breasts of any fat and cut a slit or pocket along the side, taking care not to cut through the flesh.
Cut the Boursin into four wedges and stuff a quarter into the pocket of each breast and press the opening together to seal.
Wrap two slices of Parma ham, just over-lapping, around each breast to cover completely, tucking the seam underneath.
Place the chicken in a shallow oven proof dish and tip in the tomatoes.
Drizzle with the olive oil and balsamic vinegar and scatter over the garlic, oregano, basil and thyme and season with salt and pepper.
Bake for 30-35 minutes or until the chicken is done and the tomatoes have begun to collapse slightly.
Allow the chicken to rest for 5 minutes. Serve either whole or sliced with the tomatoes and pan juices drizzles over.
This is delicious served on a bed of cooked pasta?tagliatelle is ideal?with a green salad or steamed vegetables.