Preheat the oven to 400°F.

Cut and remove ½-inch from each end of the zucchini. Using a mandoline, cut zucchini lengthwise into ⅛-inch thick slices. (You can also use a knife, just be careful!) You should have about 24 slices.

Line a large baking sheet with paper towels. Lay zucchini flat, it’s ok if the pieces overlap slightly, and sprinkle with ½ teaspoon salt. Let sit for at least 15 minutes.

In a large saucepan, heat 1 tablespoon of oil over medium heat. Add onion and cook for 2 minutes. Add minced garlic and continue cooking for another 30 seconds, or until fragrant.

Push the onion and garlic to the side of the skillet and add ground beef. Cook, breaking apart with a wooden spoon or spatula, for about 7-8 minutes. Meanwhile, line a plate with paper towels. Once beef is no longer pink, transfer to the paper towel-lined plate, leaving any residual grease in the pan.

In a large bowl combine 1 cup mozzarella, ricotta, Parmesan cheese, egg, Italian seasoning, remaining ½ teaspoon salt, and black pepper. Mix until well combined. Add the meat mixture to the cheese mixture and stir with a spatula until well mixed.

Pour half of the marinara sauce into the bottom of a 9-inch square or 7 x 11-inch baking dish.

Pat zucchini dry with additional paper towels. Spread 1 ½ tablespoons of the meat and cheese mixture along a zucchini slice. Roll zucchini slice up and place in the baking dish. Repeat with remaining cheese mixture and zucchini slices. Pour remaining marinara sauce over the roll-ups and top with 1 cup mozzarella cheese.

Bake for 25-30 minutes, or until the cheese begins to brown slightly. Serve with fresh parsley and enjoy!