01 - Preheat the oven to 400°F. Line a baking dish with parchment paper or lightly grease it.
02 - Slice each zucchini in half lengthwise. Use a spoon to scoop out the pulp, leaving a 1/2-inch border to create boats. Finely chop the zucchini pulp and set aside.
03 - Heat olive oil in a large skillet over medium heat. Add onion and cook for 2–3 minutes until softened. Stir in garlic and cook for 30 seconds.
04 - Add ground turkey to the skillet. Cook, breaking up the meat, until no longer pink, about 5 minutes.
05 - Stir in the chopped zucchini pulp and spinach. Cook for 2–3 minutes until the spinach wilts and moisture evaporates.
06 - Remove from heat. Stir in basil pesto, salt, and pepper until well combined.
07 - Arrange zucchini boats in the prepared dish. Spoon the turkey and spinach mixture evenly into each boat.
08 - Sprinkle mozzarella and Parmesan cheese over the stuffed zucchinis.
09 - Bake for 20–25 minutes, until the zucchini is tender and the cheese is bubbly and golden.
10 - Let cool for 5 minutes before serving.