1. Heat the oven to 200C/fan 180C/gas 6. Cook the onions in a knob of butter in a large pan, until soft, caramelised and dark golden. Add the garlic and spinach and cook until the spinach is completely wilted. cool.
2. Mix in the ricotta, lemon zest and half the parmesan and season. Divide between 8 pancakes and roll each one up to make an evenly-filled tube.
3. Spread 1/3 of the sauce on the bottom of a baking dish. Sit the pancakes side by side in the dish (like cannelloni). Pour the rest of the sauce over. Sprinkle over the rest of the parmesan. Bake for 25-30 minutes until bubbling and the cheese is golden.