Preheat oven to 375°F (190°C). Lightly grease a 9x9-inch baking dish with olive oil.

In a medium bowl, combine oregano, smoked paprika, garlic powder, salt, and black pepper. Toss chicken pieces in the seasoning until well coated.

Heat olive oil in a large skillet over medium-high heat. Add chicken and sear for 3 to 4 minutes per side until golden. Transfer to a plate.

Reduce heat to medium. Add chopped onion and sauté for 3 minutes until softened.

Add minced garlic and cook for 30 seconds while stirring constantly.

In a separate bowl, whisk together eggs and Greek yogurt until smooth. Season lightly with salt and pepper.

Return chicken to the skillet and stir together with the onion and garlic mixture. Remove from heat.

Layer half of the zucchini in the bottom of the prepared baking dish.

Spread half of the chicken-onion mixture over the zucchini.

Pour half of the yogurt-egg mixture evenly on top.

Sprinkle with half of the mozzarella and Parmesan cheese.

Repeat layers with remaining zucchini, chicken mixture, yogurt mixture, mozzarella, and Parmesan.

Cover loosely with foil and bake for 20 minutes.

Remove foil and bake an additional 10 to 15 minutes until cheese is melted and lightly golden.

Let casserole rest for 5 minutes before slicing.

Garnish with fresh parsley or basil if desired and serve warm.