Preheat your oven to 375°F (190°C) and grease a large baking dish with olive oil.
In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the diced onion and sauté for about 3 minutes until translucent.
Stir in the minced garlic, cooking for an additional 1 minute until fragrant.
Add the chicken thighs to the skillet, season with salt, pepper, oregano, smoked paprika, and thyme. Sear the chicken for about 5 minutes on each side until golden brown.
In the greased baking dish, spread the rinsed quinoa evenly at the bottom. Layer the seared chicken thighs on top.
In a separate bowl, mix the chicken broth, drained diced tomatoes, chopped red bell pepper, and sliced zucchini. Pour this mixture over the chicken and quinoa in the baking dish.
Scatter the crumbled feta cheese and Kalamata olives on top of everything. Drizzle with the remaining tablespoon of olive oil.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
After 30 minutes, remove the foil and bake for an additional 15 minutes or until the quinoa has absorbed the liquid and the chicken is cooked through.
Once done, let it rest for 10 minutes, then garnish with fresh parsley before serving.
Notes
Let the casserole rest before serving for better flavor.