Season the chicken with oregano, paprika, garlic powder, salt, and pepper.
Heat olive oil in a large skillet over medium-high heat. Sear the chicken for 4–5 minutes per side until golden. Remove and set aside.
In the same skillet, sauté the onion for 3 minutes. Add the garlic and cook for 30 seconds.
Stir in the orzo and toast for 1–2 minutes.
Pour in the chicken broth, then add the cherry tomatoes and olives. Stir well.
Return the chicken to the skillet, nestling it into the orzo.
Cover and simmer over low heat for 12–15 minutes, until the orzo is tender and the chicken reaches an internal temperature of 165°F (74°C).
If using spinach, stir it in during the last 2 minutes until wilted.
Remove from the heat and stir in the lemon zest and lemon juice.
Sprinkle with feta cheese and fresh parsley before serving.
