Preheat oven to 400F and grease a 9x13-inch baking dish.
Cut chicken into bite-sized pieces and add to the dish. Toss with olive oil, Dijon mustard, garlic, oregano, thyme, garlic powder, salt, and pepper.
Add tomatoes, chopped bell pepper, zucchini, olives, and ½ cup feta.
Whisk chicken broth and Greek yogurt, then add to the dish along with orzo.
Stir well, ensuring orzo is mostly submerged.
Bake uncovered for 35–40 minutes, until orzo is tender and chicken is cooked.
Stir in the remaining feta, lemon juice, and parsley.
Let it sit for 10–15 minutes to thicken. Taste and adjust salt if needed. Serve.