Using a mandoline slicer slice the zucchini about 1/8 inch thick. I use setting 2 on this slicer. Place the sliced zucchini on paper towels to absorb moisture as you work.

Pre cook the zucchini. You can do this using the skillet method or the oven method:
Skillet method: Heat a large skillet, griddle or grill to medium heat. Lightly spray the cooking surface with oil and grill the zucchini 1-2 minutes on each side until they have begun to brown and there is very little steam coming off the zucchini. This helps to remove the moisture which will prevent the dish from being soggy. Place the cooked zucchini noodles on paper towels to absorb any extra moisture.
Oven method: Place the zucchini slices on a lightly greased baking sheet and bake at 400 degrees F for 10-15 minutes, flipping half way through while you prepare the rest of the lasagna. Remove the zucchini from the oven when they have browned slightly and very little steam is coming off the zucchini. Place the cooked zucchini noodles on paper towels to absorb any extra moisture.

Preheat the oven to 400 degrees F. Grease an 11x7 baking dish and set aside.

Brown the Italian sausage and ground beef over medium heat and drain off any grease. Add the marinara sauce to the skillet and reduce the heat to low. Allow the mixture to simmer while you prepare the rest of the ingredients.

In a mixing bowl combine the ricotta, parmesan, egg, garlic and Italian seasoning.

In a greased 11x7 baking dish spread 1/2 cup of the meat sauce in the bottom of the dish. Place the zucchini noodles on top (10-12 slices), then the ricotta mixture, a meat sauce layer, zucchini noodles, ricotta, meat sauce and top with the mozzarella cheese.

Bake the lasagna uncovered 25-30 minutes until the cheese is gold and bubbly. Let the lasagna sit 10 minutes before serving, do not skip this step, the dish needs time for any moisture to settle.