Pre-heat the oven 200°C.
Spoon the cheese into the empty tomatoes and sprinkle with the dried thyme and some seasoning. Arrange in a roasting tray and drizzle with the olive oil.
Replace the reserved tops and bake for 15 minutes until the cheese is melting and the tomatoes are soft. Remove from the oven and cover with tin foil to keep warm.
Heat a frying pan over a moderate heat until hot and dry fry the pancetta until golden and crispy. Drain on kitchen paper. Arrange the salad on serving plates and sprinkle over the pancetta. Sit a tomato in the centre and serve.