Prep the zucchini: Preheat the oven to 400°F (200°C). Slice the zucchini in half lengthwise. Use a spoon to scoop out the centers, leaving about 1/4-inch border to form “boats.” Chop the scooped zucchini flesh and set aside.
Place the zucchini boats on a baking sheet or in a baking dish, brush with 1 tablespoon olive oil, and sprinkle with salt and pepper.
Par-bake the boats: Bake the oiled zucchini shells for 8–10 minutes until slightly tender but not fully cooked. This helps them finish evenly once stuffed.
Sauté aromatics: While the boats bake, heat the remaining 1 tablespoon olive oil in a large skillet over medium heat. Add the onion and cook 3–4 minutes until translucent.
Stir in the garlic and cook 30 seconds, just until fragrant.
Cook the chicken: Add ground chicken, season with salt and pepper, and break it up with a spoon. Cook 5–7 minutes until no pink remains.
Add chopped zucchini and seasoning: Stir in the reserved chopped zucchini flesh, oregano, cumin, and red pepper flakes. Cook 3–4 minutes to soften and reduce excess moisture.
Finish the filling: Remove the pan from heat.
Stir in tomatoes, olives, lemon zest, lemon juice, parsley, dill, and feta. Taste and adjust with more salt, pepper, or lemon juice as needed.
Stuff and top: Spoon the filling into the par-baked zucchini boats, mounding slightly. Sprinkle with a little extra feta and Parmesan if using.
Bake: Return to the oven for 12–15 minutes, until the zucchini is tender and the tops are lightly golden.
If you want more color, broil for 1–2 minutes at the end, watching closely.
Serve: Let rest 3–5 minutes. Garnish with extra parsley or dill. Serve with a dollop of Greek yogurt or tzatziki and lemon wedges.