In a large pot, heat the olive oil over medium heat. Add the diced chicken breast and season with salt, pepper, oregano, and paprika. Sauté until the chicken is cooked through and no longer pink, about 5-7 minutes.
Add the chopped onion and minced garlic to the pot, stirring until the onion becomes translucent, approximately 3-4 minutes.
Stir in the bell pepper and cherry tomatoes, cooking for another 2-3 minutes until the vegetables start to soften.
Add the orzo pasta to the pot, followed by the chicken broth. Bring to a simmer, then reduce the heat to low, covering the pot. Allow it to cook for about 10 minutes, or until the orzo is tender and has absorbed most of the broth.
If using frozen spinach, add it now, and stir to combine. If using fresh spinach, fold it in just before serving so it wilts but retains some volume. Cook for an additional 1-2 minutes.
Once everything is well combined and heated through, remove from heat. Taste and adjust seasoning if necessary.
Serve hot, garnished with chopped parsley.