This vegetarian porcini mushroom and tomato pasta bake is flavoured with smoked mozzarella. If you can't get your hands on fresh porcini mushrooms, you can use frozen mixed mushrooms which are available in most supermarkets. Baked pasta will always taste better when it is prepared ahead of time to let the flavours blend. For traditional Sunday family lunch, Italian mums prepare this dish in the morning or even the day before, then reheat slowly when ready to serve.
Parmesan cheese is not truly vegetarian, as it contains animal rennet. To make this dish 100% vegetarian, omit the cheese or find a suitable vegetarian substitute made without animal rennet. In supermarkets look for the 'parmesan style hard cheeses' which are suitable for vegetarians.