Preheat the oven to 400°. Salt and pepper the chicken.
Heat the olive oil in a large cast iron pan or dutch oven. Cook the chicken for 4 minutes each side until slightly browned. Then transfer it to a plate.
Using the same pan, add the butter, garlic and orzo. Cook for 3 minutes. Add in the wine, and stir around to get any brown bits off of the pan.
Add in the stock, sun-dried tomatoes, oregano, lemon zest and lemon juice. Bring to a boil.
Mix in the baby spinach. Add the chicken back in, including any juices off of the plate.
Transfer to the oven and cook for an additional 15 minutes. Make sure the chicken is fully cooked.
Serve immediately!