Preheat the fan oven from top and bottom to 360-400 ºF.
Grease an oven dish with a 20-23cm base with olive oil. Using a spoon, spread the tomato sauce over the dish. Set aside.
Then, slice the zucchini from top to bottom in long strips using a vegetable peeler.
Place the ricotta, egg yolk, garlic, lemon peel and chopped basil leaves in a bowl. Add salt and pepper. Mix well using a spoon or fork.
Spread the strips of zucchini over a wooden board. On top of them, place 2 tablespoons of the ricotta and basil mixture. Make sure that you spread the mixture well from one end to the other on each of the zucchini strips.
Now roll up the zucchini strips, and place them one by one in the oven dish in which you spread the tomato sauce. You will have about 12 zucchini cannelloni.
Sprinkle the mozzarella and parmesan cheese over the top, as well as the olive oil.
Put the oven dish in the oven for 25 or 30 minutes, or until the cannelloni and cheese are golden. Before serving, you can decorate the plate with fresh basil leaves and add a dash of organic extra virgin olive oil for more flavor.