1. Heat the oven to 200C/180C fan/gas 6. Warm 3 tbsp olive oil in a pan over a medium heat, then add the garlic and fry for 1 min. Add the chopped tomatoes, along with the tomato juice from one can, then add the basil and simmer for 25 mins.
2. Slice the courgettes in half lengthways, then use a teaspoon to scoop out the pulp from each into a bowl. Using your hands, squeeze the excess liquid from the courgette pulp into a bowl, then discard the liquid and use a knife to roughly chop the remains. Heat 2 tbsp olive oil in a frying pan then add the red onion and fry for 2 mins. Once softened, add the turkey and stir in the courgette pulp, then fry for another 2 mins. Add the parsley, plus some salt and freshly ground black pepper, then remove from the heat and allow to cool. Once cool, transfer to a large bowl and use your hands to combine with the bread, parmesan and egg. Fill the courgette shells with this mixture.
3. Pour the tomato sauce into an ovenproof dish, place the filled courgettes on top, then drizzle with the extra olive oil. Cover with foil and bake in the oven for about 35 mins, or until the courgettes are cooked through. Remove the foil, sprinkle over the breadcrumbs and continue to bake uncovered for another 5 mins. Serve immediately. Season to taste.