01 - Preheat oven to 400°F. Line a baking dish with parchment paper or lightly grease it.
02 - Slice the zucchini in half lengthwise. Using a spoon, carefully scoop out the flesh, leaving about 1/2 inch border to create boats. Chop the scooped-out flesh and set aside.
03 - Place the zucchini boats cut side up in the prepared baking dish. Drizzle with 1 tbsp olive oil and season lightly with salt and pepper.
04 - Heat the remaining 1 tbsp olive oil in a large skillet over medium heat. Add onion and cook until softened, about 3 minutes. Add garlic and cook for 1 minute more.
05 - Add ground beef, breaking it up with a spoon. Cook until browned, about 5–7 minutes. Drain excess fat if needed.
06 - Stir in diced tomato, chopped zucchini flesh, tomato paste, Italian herbs, paprika, salt, and pepper. Cook for 3–4 minutes until vegetables are tender and mixture is thickened.
07 - Spoon the beef mixture evenly into the zucchini boats. Sprinkle mozzarella and Parmesan cheese over the top.
08 - Cover with foil and bake for 20 minutes.
09 - Remove foil and bake an additional 8–10 minutes, or until cheese is golden and bubbly.
10 - Garnish with fresh parsley before serving, if desired.