Preheat oven to 160C.
To make the sauce, cut up the carrots, celery, 1/2 the onion and garlic. Add to a pan with a little oil, cook until softening.
Add the paprika, Passata, oregano and some black pepper. Cover and let simmer until veg is fully soft. When cooked, blend with a wand or a blender until smooth. Transfer into your baking/ roasting tin. Sprinkle with the rest of the chopped onion and fresh basil. Set aside
Wilt the spinach in a pan with a bit of water, strain excess water by pushing the spinach through the sieve.
Slice the courgette with a peeler.
In a bowl add the ricotta, spinach and some black pepper. Mix well.
Place one slice of courgette on the surface and spread some of the ricotta mixture along with it, take hold of one end, and gently roll up, careful not to squeeze out the filling. Add the rolls to the sauce and bake for 10 mins. Take out and sprinkle with the mozzarella and put back in the oven for a further 15 mins or until starting to brown