Prep the oven and pan: Preheat the oven to 400°F (200°C). Lightly oil a large baking dish with 1 tablespoon olive oil.

Prepare the zucchini: Trim the ends, slice each zucchini in half lengthwise, and use a spoon to scoop out the centers to create “boats.” Leave about 1/4 inch of flesh for structure. Reserve about half the scooped zucchini, finely chop it, and set aside.

Season the boats: Brush the zucchini shells with the remaining olive oil and season with a pinch of salt and pepper. Place them cut side up in the baking dish.

Par-bake for texture: Bake the empty zucchini boats for 10 minutes to soften slightly. This helps them cook through without getting watery.

Cook the beef: While the boats bake, heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it up, until browned and no longer pink, about 5–7 minutes. Drain excess fat if needed, leaving about 1 tablespoon in the pan.

Add aromatics and zucchini: Stir in the onion and cook 3 minutes until softened. Add the garlic and the chopped zucchini flesh. Cook another 2–3 minutes until most of the moisture cooks off.

Season and sauce: Stir in the marinara, tomato paste, Italian seasoning, smoked paprika, red pepper flakes, and a good pinch of salt and pepper. Simmer 2–3 minutes to thicken slightly. Taste and adjust seasoning.

Fill and top: Spoon the beef mixture evenly into the par-baked zucchini boats. Sprinkle with mozzarella, then Parmesan.

Bake until bubbly: Return the pan to the oven and bake 12–15 minutes, until the cheese is melted and golden and the zucchini is tender but not mushy.

Finish and serve: Let rest 5 minutes. Garnish with chopped parsley or basil. Serve warm.