- Cut zucchini in half lengthwise and scoop out flesh inside using a melon baller. Set flesh aside.
- Season inside of zucchini with salt and place with cut side facing bottom on a paper towel. Set aside.
- In a skillet set over medium heat, sauté onion, zucchini flesh, and garlic in olive oil for 5 minutes, stirring occasionally. Add sausage meat and continue cooking for 5 minutes. Season with salt and pepper to taste. Add pepper flakes (if using).
- Refrigerate mixture for 15 minutes and then add basil, 250 mL (1 cup) of mozzarella, Parmesan, and bread crumbs. Mix well to combine.
- Preheat oven to 190°C (375°F).
- Pat inside of zucchini dry and stuff generously with mixture, pressing down gently.
- Line the base of a 22.5 x 32.5 cm (9 x 13 in.) baking dish with parchment paper. Place stuffed zucchini and sprinkle with remaining mozzarella. Bake for 30 to 35 minutes, according to the size of the zucchini.
To check zucchini doneness, insert the tip of a knife into flesh. They’re ready when tender but still firm.
Serve hot or warm with a side of seasonal lettuce, pasta salad, or cherry tomatoes.