01 - Preheat oven to 400°F. Line a baking dish with parchment paper or lightly grease it.
02 - Slice zucchini in half lengthwise and use a spoon to scoop out the center, creating boats. Reserve the scooped flesh and chop it.
03 - Heat olive oil in a large skillet over medium heat. Add onions and cook 2–3 minutes until softened. Add garlic, mushrooms, and chopped zucchini flesh; cook another 3–4 minutes until tender.
04 - Add ground turkey to the skillet. Cook, breaking up the meat, until no longer pink, about 5–6 minutes. Season with salt and pepper.
05 - Stir in basil pesto and parsley. Remove from heat.
06 - Arrange zucchini boats in the prepared baking dish. Fill each boat with the turkey-mushroom mixture.
07 - Sprinkle mozzarella and Parmesan evenly over the stuffed zucchini.
08 - Bake for 20–25 minutes, until zucchini is tender and cheese is golden and bubbly.
09 - Serve hot, garnished with extra parsley if desired.