Take the tomatoes off the vine, wash and dry them, and put them in a bowl. Add the olives, chilli, garlic, half the oregano and the oil to the tomatoes.
Leave to marinade for an hour or so.
Preheat oven to 180C. Tip contents of bowl into shallow ovenproof dish, season and cook in oven for 30 mins, until tomatoes start to burst. Meanwhile, cook pasta until al dente. Drain and put in serving bowl.
Add remaining oregano and mozzarella, then tip in the tomatoes, mix together and serve.