Preheat oven to 400°F (200°C). Trim ends of zucchini and slice each lengthwise. Scoop out seeds and some flesh to create boats, reserving the scooped flesh and chopping it for the filling. Brush insides with a little olive oil and roast cut-side down for 8–10 minutes.

Heat 1 tbsp olive oil in a skillet over medium heat. Sauté onion until translucent, add garlic and cook 30 seconds. Add ground meat (or cooked quinoa) and chopped zucchini flesh; cook until browned. Stir in tomatoes, oregano, paprika, salt, and pepper. Simmer until most liquid reduces, about 6–8 minutes.

Spoon the filling into the roasted zucchini shells, mound slightly, and top with mozzarella, Parmesan, and breadcrumbs if using. Bake for 10–12 minutes until cheese is melted and golden. Broil 1–2 minutes for extra color if desired.

Let the zucchini boats rest for a couple minutes, garnish with fresh basil or parsley, and serve warm.