Step 1

Heat oil in a large heavy-based saucepan over high heat; cook onion, celery, carrot, prosciutto and garlic, stirring, for 5 minutes or until onion is soft. Add pork and veal; cook, stirring, to break up lumps, for 10 minutes or until browned.

Step 2

Stir in paste and oregano; cook, stirring, for 2 minutes. Add wine, bring to the boil; cook for 4 minutes or until reduced by half. Stir in passata, stock, rosemary, thyme and parmesan rind; bring to the boil. Reduce heat to low; cook, covered, stirring occasionally, for 1½ hours or until thickened. Season. Remove and discard parmesan rind from sauce.

Step 3

Cook spaghetti in a large saucepan of boiling salted water for 8 minutes or until just tender; drain.

Step 4

Finely grate remaining parmesan. Serve spaghetti topped with bolognese sauce, sprinkled with grated parmesan and fresh oregano leaves, if you like.