In a large skillet, heat the olive oil over medium heat. Add the diced chicken breast, seasoning it with salt, pepper, and Italian seasoning. Sauté until the chicken is golden brown and cooked through, about 7-8 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, add the chopped onion and minced garlic. Sauté until the onion becomes translucent, about 3-4 minutes.
Stir in the chopped sun-dried tomatoes and cook for another 2 minutes.
Add the orzo pasta to the skillet and stir for about 1 minute to lightly toast the pasta.
Pour the chicken broth into the skillet, bringing the mixture to a boil. Reduce the heat to low and let it simmer for about 10 minutes, or until the orzo is tender and most of the liquid has been absorbed.
Once the orzo is cooked, return the cooked chicken to the skillet. Stir in the chopped spinach and let it wilt into the mixture, about 2 minutes.
Remove the skillet from heat and stir in the feta cheese, allowing it to slightly melt and blend with the dish. Adjust seasoning with salt and pepper if needed.
Serve hot, garnished with fresh basil leaves for an aromatic finish.