Finely chop the herbs or spinach, or a combination of both. To make the filling for the cannelloni, combine both Ricottas, the herbs and/or baby spinach, Grated Parmesan and egg in a large bowl. Stir until completely combined.
Lay a fresh lasagna sheet onto a piece of baking paper. Along one end, smooth two to three tablespoons of the filling mixture. Roll the mixture into the centre of the sheet and cut if there is too much excess. Repeat this process until all filling is used.
Pour a third of the passata into a 25 x 30 centimetre ovenproof dish, then place each cannelloni with seam side down into sauce. Be sure to pack snugly so that they hold together during baking.
Pour remaining sauce over the cannelloni. Grate the Mozzarella over the top of the cannelloni.
Cover the tray with baking paper and foil. Bake for 35 to 45 minutes, removing foil for the final 15 minutes until the tops turn golden brown. Rest for five minutes prior to serving, but be sure to serve hot.