01 - Preheat the oven to 400°F. Lightly grease a large baking dish and set aside.
02 - Cut the zucchinis in half lengthwise. Using a spoon, carefully scoop out the centers to form boats. Reserve the scooped flesh and chop it finely.
03 - Heat olive oil in a large skillet over medium heat. Add the diced onion and cook for 2 minutes until softened.
04 - Add the minced garlic and cook for 30 seconds until fragrant. Stir in the chopped mushrooms and reserved zucchini flesh. Sauté for 4 to 5 minutes until tender and most of the moisture has evaporated.
05 - Add the ground turkey to the skillet, breaking it apart with a spoon. Cook for 5 to 6 minutes until no longer pink and evenly browned.
06 - Stir in the basil pesto, dried oregano, salt, and pepper. Simmer for 2 minutes to meld the flavors. Remove from heat and fold in half of the torn fresh basil.
07 - Arrange the hollowed zucchini boats in the prepared baking dish. Generously fill each boat with the turkey and mushroom mixture.
08 - Sprinkle the shredded mozzarella and grated Parmesan evenly over the filled zucchini boats.
09 - Bake for 20 to 25 minutes until the zucchini is tender and the cheese is golden and bubbling.
10 - Remove from the oven and garnish with the remaining fresh basil leaves before serving.