Preheat the oven to 400℉ (200°C). Prepare a 9x13 inch baking dish by spraying cooking spray on the bottom of the pan.
Cut the chicken breasts into bite-sized pieces. Add the chicken to the large baking dish and coat it in the olive oil, dijon mustard, and seasonings. Be sure all the chicken pieces are coated.
Prep the vegetables by chopping the bell pepper and zucchini and mince the garlic. No need to chop the cherry tomatoes or olives. Add the tomatoes, zucchini, bell pepper, kalamata olives, garlic, and half a cup of the feta cheese to the dish with the chicken.
Whisk the Greek yogurt and chicken broth together. Add the orzo and chicken broth mixture on top of the chicken and vegetables. Then stir everything together with a wooden spoon.
Bake in the preheated oven for 35-40 minutes or until the orzo is tender and the chicken reaches an internal temperature of 165℉ (75°C). Cooking time will vary.
Stir in the remaining feta cheese, lemon juice, and parsley when it comes out of the oven and give it a quick taste. Add more salt as needed then let it set for 10-15 minutes before serving.
