Preheat the oven to 180°C, fan 160°C, gas 4. Place the spinach in a large pan with 1 tbsp water; place over a medium heat and cook until wilted. Drain. Set aside.
Heat the oil in a pan. Fry the onion for 5-6 mins until soft but not coloured. Stir in the garlic and cook for a few mins. Transfer half of the mixture to a bowl and set aside. Add the passata to the pan of onion and garlic. Add 200ml of water to the jar to rinse out any remaining passata. Pour into the pan, add half the basil and a grinding of black pepper. Simmer for 5 mins. Set aside.
Using your hands, squeeze the excess water from the spinach then chop. Add to the onion and garlic in the bowl, along with the pork, breadcrumbs and remaining basil. Mix until combined. Fill the cannelloni with the pork and spinach stuffing, using your fingers to add a little at a time to each end of the tubes.
Divide the tomato sauce between two 1 or 1.5-litre ovenproof dishes. Lay the filled cannelloni in a single layer on the sauce, pressing down so that they’re covered.
Mix the créme fraîche with 50ml water, to loosen it to a pouring consistency, and pour over the top of the cannelloni and sauce. Scatter the torn mozzarella on top and then sprinkle over the parmesan.
If you're freezing one portion, cover the dish with clingfilm, then foil, and freeze for up to 3 months. Cover the second with foil and bake for 30 mins, then remove foil and bake for a further 15 mins until the top is golden and bubbling.
To cook the frozen portion, defrost it completely (overnight in the fridge is best) then remove the layer of clingfilm, reuse the foil, and bake at 180°C, fan 160°C, gas 4 for 30 mins. Remove the foil and bake for a further 15 mins.
Tip: cut then mash the filled cannelloni until it combines with the sauce and you have a creamy, coarse mash. Or, for younger babies, purée the mixture.