Step 1 Combine mince, parsley and breadcrumbs in a bowl. Roll tablespoons of mixture into balls.
Step 2 Spray a large frying pan with oil and place over medium-high heat. Cook meatballs, in batches, for 2–3 minutes until browned all over (meatballs do not need to be cooked through). Remove and set aside.
Step 3 Spray a large saucepan with oil and place over medium heat. Add onion, carrot and celery. Cook, stirring occasionally, for 6–7 minutes, or until soft. Add garlic and mushrooms; cook, stirring, for 2–3 minutes. Add passata, bring to the boil and simmer for 10 minutes. Remove from heat and set aside to cool slightly.
Step 4 Meanwhile, cook spaghetti according to packet instructions. Drain well.
Step 5 Using a stick blender, blend sauce until smooth. Add pasta and meatballs to sauce and simmer over low heat for 10 minutes. Garnish with extra parsley and serve with salad.