Wash and dry the tomatoes and cut in half crosswise. Mix the thyme with pepper, salt and 2 tbsp olive oil and brush the cut surface of the tomatoes with it.
Crumble the bread chips, finely chop the olives and mix together with the rest of the olive oil and the parmesan.
Grill the tomatoes with the cut surface down, for about 3 minutes, then turn, season lightly with salt and spread the bread chip mixture over the cut surfaces. Grill for a further 3 minutes and serve immediately.