Preheat oven 220ºC. Lightly grease 5cm deep, 22cm x 30cm base baking dish. Heat oil in a large frying pan over medium-high heat. Add garlic and mushrooms. Cook, stirring occasionally for 5 minutes or until tender.
Add tomatoes and bring to the boil. Remove from the heat.
Chop 34 cup basil leaves and stir into mushroom mixture. Season with salt and pepper.
Meanwhile, cook the pasta in a large saucepan of boiling salted water for 3 minutes. Drain and spoon into prepared dish. Add mushroom mixture and stir to coat the pasta.
Tear the bocconcini in half and arrange over the pasta. Sprinkle with parmesan. Bake 15 minutes or until piping hot. Top with remaining basil leaves. Season with pepper. Serve.