01 - Set oven to 375°F for baking the stuffed zucchini boats.
02 - Cut zucchinis lengthwise and scoop out pulp, leaving 1/2-inch thick shells. Chop the reserved pulp.
03 - Heat olive oil in skillet over medium heat. Sauté onion 2-3 minutes until softened, add garlic and cook 30 seconds.
04 - Add ground beef to skillet, breaking apart with spoon. Cook 5-6 minutes until browned. Drain excess fat if needed.
05 - Mix in chopped zucchini pulp, diced tomato, tomato paste, oregano, basil, salt, and pepper. Cook 4-5 minutes until combined and liquid is absorbed.
06 - Remove from heat. Stir in breadcrumbs, Parmesan cheese, and fresh parsley until evenly distributed.
07 - Place zucchini halves in baking dish. Fill each shell with beef mixture, pressing gently to pack tightly.
08 - Sprinkle mozzarella cheese evenly over stuffed zucchini boats.
09 - Cover baking dish with foil. Bake at 375°F for 20 minutes.
10 - Remove foil and continue baking 10-15 minutes until cheese is golden and bubbly.
11 - Garnish with additional fresh parsley. Serve hot.