01 - Preheat oven to 400°F. Lightly grease a medium baking dish with cooking spray or a small amount of olive oil.
02 - Heat 1 tbsp olive oil in a large skillet over medium-high heat. Season chicken pieces with salt, pepper, and smoked paprika. Sauté for 4–5 minutes until lightly golden but not cooked through. Transfer to a plate.
03 - In the same skillet, add remaining olive oil. Sauté onion for 2 minutes until softened, then add garlic and cook until fragrant, about 30 seconds.
04 - Add zucchini and sun-dried tomatoes to the skillet. Cook for 3–4 minutes until zucchini is just starting to soften.
05 - Stir in spinach and cook until just wilted. Remove skillet from heat.
06 - In a bowl, combine heavy cream, oregano, basil, chili flakes (if using), half the feta, and half the mozzarella. Season with salt and pepper.
07 - Arrange sautéed vegetables and chicken pieces in the prepared baking dish. Pour cream mixture evenly over the top.
08 - Sprinkle with remaining feta, mozzarella, and all the Parmesan cheese.
09 - Bake for 25–30 minutes, or until chicken is cooked through and the top is golden and bubbling.
10 - Let the dish rest for 5 minutes before garnishing with fresh basil leaves and serving.