Wash the spinach and shake dry. Briefly blanch in boiling salted water, then drain and rinse under cold running water. Drain again, pressing out all the excess water.
Finely chop the spinach.
Cut off the crusts from the toast and finely dice.
Drain the ricotta and mix with the spinach, toast and eggs. Season with salt, pepper and freshly grated nutmeg.
Fill a disposable piping bag fitted with a plain nozzle with the spinach mixture.
Fill the cannelloni with the spinach mixture and place in an ovenproof dish (22 x 15cm). Pour over the tomato sauce and bake in the preheated oven at 180°C (160°C fan, gas 4). Grate the parmesan and sprinkle over the cannelloni after 20 minutes.