01 - Preheat oven to 400°F (200°C).
02 - Cut zucchini in half lengthwise. Scoop out the center flesh leaving a ½ inch shell, then chop the reserved flesh.
03 - Place zucchini halves cut-side up in a baking dish. Drizzle with 1 tbsp olive oil and season lightly with salt and pepper.
04 - Heat remaining 1 tbsp olive oil in a skillet over medium heat. Sauté onion until soft, approximately 3 minutes. Add garlic and cook for 30 seconds.
05 - Add ground beef to skillet and brown, breaking it up, for 5 to 6 minutes. Drain excess fat if necessary.
06 - Stir in chopped zucchini flesh, diced tomato, tomato paste, oregano, basil, paprika, salt, and pepper. Cook mixture for 5 minutes until vegetables soften and sauce thickens.
07 - Spoon the beef mixture evenly into zucchini shells. Top with shredded mozzarella cheese.
08 - Cover baking dish with foil and bake for 20 minutes.
09 - Remove foil and bake an additional 5 to 10 minutes until cheese is golden and bubbly.
10 - Optionally garnish with chopped parsley prior to serving.