Preheat oven 200°C/180°C fan forced. Squeeze spinach to remove excess water; place in a large bowl with mince, breadcrumbs, parmesan, eggs, parsley and onion. Mix well.
Lay a large sheet of foil onto a bench; cover with baking paper; spread mince mixture onto baking paper and shape into a 25cm long, six cm high log. Wrap with foil and baking paper. Place on a baking tray and bake for 35 minutes; unwrap and cook for a further 10 minutes or until golden.
Meanwhile, place oil, tomatoes and garlic in a medium saucepan over high heat; simmer 10 minutes; add basil; cook a further 5 minutes; place in a food processor or blender and blend until smooth. Serve with meatloaf.
This meatloaf is generous enough for leftovers and sandwiches the next day!