Cut 20 x 1½ cm cubes from the Mozzarella block. Reserve remaining Mozzarella for another use

To make meatballs, combine all ingredients except Mozzarella in a large bowl. Season with salt and pepper. Mix well. Roll level tablespoons of mixture to form 20 meatballs

Press one cube of Mozzarella into the centre of each ball, then roll to enclose cheese and reshape into balls. Refrigerate until required

Cook pasta in a large saucepan of boiling, salted water for about 9 - 10 minutes, or until tender. Drain, reserving ¾ cup of the cooking water

Meanwhile, heat half the oil in a large, deep non-stick frying pan over a medium-high heat. Add meatballs. Cook, turning occasionally, for about 4 minutes, or until browned all over. Remove from pan

Add onion and remaining oil to pan. Cook, stirring over a medium heat for 3 minutes, or until soft. Stir in paste. Add passata and reserved cooking water. Return meatballs. Bring to the boil. Simmer for about 10 minutes, or until sauce is thickened slightly and meatballs are cooked through. Remove from heat

Serve meatballs and sauce over spaghetti. Sprinkle with grated Parmesan and garnish with basil leaves