01 - Preheat oven to 400°F. Line a baking sheet or large baking dish with parchment paper.
02 - Slice zucchini in half lengthwise. Using a spoon, carefully scoop out the center flesh to create hollow boats. Reserve the scooped flesh for the filling.
03 - Heat olive oil in a large skillet over medium heat. Add diced onion and cook for 2–3 minutes until softened. Add minced garlic and cook for 30 seconds until fragrant.
04 - Add ground turkey to the skillet, breaking it apart with a spoon. Cook for 5–6 minutes until browned and cooked through.
05 - Stir in chopped spinach, reserved zucchini flesh, salt, pepper, and dried Italian herbs. Cook for 2–3 minutes until spinach is wilted and the mixture is evenly combined.
06 - Remove skillet from heat. Fold in basil pesto and 2 tablespoons of Parmesan cheese until well incorporated.
07 - Arrange zucchini halves on the prepared baking sheet. Generously fill each boat with the turkey-spinach mixture.
08 - Sprinkle shredded mozzarella evenly over each filled boat. Bake for 18–22 minutes until zucchini is tender and cheese is melted and golden.
09 - Remove from oven, garnish with fresh basil leaves, and serve immediately while hot.