01 -
Preheat the oven to 400°F (200°C).
02 -
Cut and remove ½ inch from each end of the zucchini. Using a mandoline, cut zucchini lengthwise into ¼-inch thick slices. You should have about 24 slices.
03 -
Line a large baking sheet with paper towels. Lay the zucchini flat (slight overlapping is acceptable) and sprinkle with ½ teaspoon salt. Let sit for at least 15 minutes to release excess moisture.
04 -
In a large saucepan, heat the olive oil over medium heat. Add onion and cook for 3-4 minutes, or until translucent. Add the garlic and continue cooking for another 30 seconds, or until fragrant.
05 -
Push the onion and garlic to one side of the skillet and add the ground beef. Cook, breaking apart for 7-8 minutes, or until no longer pink. Line a plate with paper towels and transfer the cooked beef to drain excess fat.
06 -
In a large bowl combine 1 cup of the mozzarella, ricotta, Parmesan cheese, egg, Italian seasoning, remaining ½ teaspoon salt, and black pepper. Stir until well combined. Add the drained meat mixture to the cheese mixture and stir until fully incorporated.
07 -
Pour half of the marinara sauce into the bottom of a 9-inch square or 7 x 11-inch baking dish, spreading to create an even layer.
08 -
Pat zucchini slices thoroughly dry with additional paper towels. Spread 1½ tablespoons of the meat and cheese mixture along each zucchini slice. Roll up and place seam-side down in the baking dish. Repeat with remaining ingredients.
09 -
Pour the remaining marinara sauce over the roll-ups and sprinkle with the remaining 1 cup mozzarella cheese.
10 -
Bake for 25-30 minutes, or until the cheese begins to bubble and brown slightly. Let rest for 5-10 minutes before serving. Garnish with fresh parsley if desired.