Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.

Slice each zucchini in half lengthwise and scoop out the flesh, leaving about a 1/4-inch border.

Finely chop the reserved zucchini flesh and set it aside for the filling.

In a skillet, heat 2 tablespoons of olive oil over medium heat. Add chopped onion and minced garlic, sautéing for 2–3 minutes until soft.

Add the ground beef, stirring until browned, about 5–7 minutes.

Mix in chopped zucchini flesh, breadcrumbs, Parmesan cheese, tomato sauce, oregano, salt, and black pepper.

Transfer the meat mixture into the hollowed zucchini halves, packing it down gently.

Sprinkle shredded mozzarella cheese on top of each stuffed zucchini boat.

Place the filled zucchini boats on the prepared baking sheet and bake for 20-25 minutes.

Remove from the oven and garnish with fresh chopped parsley before serving.