Preheat your oven to 190°C (375°F) and lightly oil a baking dish to prevent sticking.
Wash the zucchinis thoroughly, then slice off the stems and cut each in half lengthwise. Use a melon baller or teaspoon to carefully scoop out the flesh, leaving about 1/4 inch border to keep the shells sturdy. Set the flesh aside to chop and use in the filling.
Finely chop the scooped zucchini flesh and set aside. In a skillet over medium heat, warm a tablespoon of olive oil and add the minced garlic. Sauté until fragrant, about 30 seconds, then toss in the chopped zucchini flesh and cook until softened and fragrant, about 3-4 minutes.
Transfer the cooked zucchini mixture to a mixing bowl. Add the cheese, breadcrumbs, chopped basil, salt, pepper, and a drizzle of olive oil. Mix well until combined; the mixture should be moist but not runny. Adjust seasoning if needed.
Stuff each zucchini shell generously with the filling, pressing it in to fill all gaps. Place the stuffed zucchinis upright in your prepared baking dish, then drizzle a little olive oil over the tops for a golden finish.
Bake in the preheated oven for 25-30 minutes, until the tops are golden-brown and bubbling. The zucchini shells should feel tender when pressed gently, and the filling should be set and slightly crispy on top.
Remove from the oven and let rest for about 5 minutes. Serve warm, garnished with additional basil or a squeeze of lemon if desired.
