Preheat the oven to 400 degrees Fahrenheit.

Slice the zucchini lengthwise into thin slices and set aside.

To make the sauce, heat a large pan over medium heat and add in olive oil. Sauté the onions and garlic until fragrant. Add in the ground beef, making sure to break down the ground beef into small pieces while cooking. When the meat is fully cooked, reduce the heat to low and add in the mushrooms and tomato sauce. Season with garlic powder, Cajun seasoning, and salt/pepper to taste. Stir and let simmer for about 5 minutes.

To layer the lasagna, cover the bottom of the casserole dish with a layer of zucchini slices, then spread half of the sauce on top followed by half of the mozzarella cheese. Repeat these layers one more time and top with the remaining cheese.

Cover with foil and bake at 400 degrees F for about 40 minutes. Then uncover and let it broil for 5 minutes to get a nice golden-brown top. Garnish with fresh parsley, serve, and enjoy!