Preheat the oven to 350 degree F. Line a baking tray with parchment paper and keep it aside.
Trim the ends and slice the zucchini lengthwise to uniform strips using a mandolin.
Place the zucchini strips on the prepared baking sheets next to each other and bake them for 20 minutes by flipping them to the other side halfway through. Set aside to cool.
Meanwhile, prepare the sauce. Heat a pan with olive oil and garlic; saute for a minute and add the onion. Cook the onion for 2-3 minutes and add the crushed tomato.
Simmer the sauce and cook for 5 minutes. Finally add in the basil, Italian sauce, pepper, and salt. Keep the sauce aside.
For the filling; combine the ricotta, parmesan, egg, black pepper, and salt in a bowl. Mix it and set it aside.
For assembling the lasagna; add 2 tablespoons of prepared sauce to a medium casserole dish. Arrange a layer of pre-baked zucchini strips. Add ⅓ cup of prepared ricotta filling followed by ¼ cup saucer and ¼ cup of mozzarella cheese. Repeat the same for three layers.
For the final layer end with Lasagna strips arranged in a criss-cross pattern. Add the remaining cheese on top and cover the lasagna with aluminum foil. Bake the lasagna for 30 minutes at 350 degrees F.
Remove the foil and bake further for 10 more minutes until the cheese is melted.
Allow the zucchini lasagna to cool for 30 minutes. Before serving, slice the lasagna and serve it warm.