Pat the chicken thighs dry and season lightly with salt and black pepper.
Heat the olive oil in a large skillet or shallow pot over medium heat. Add the chicken and cook for about 4–5 minutes per side, until nicely browned. Remove the chicken from the pan and set aside.
Add the diced onion to the same pan and cook for 2–3 minutes, until beginning to soften.
Add the peeled, diced Roma tomatoes and cook for another 2–3 minutes, until they begin to break down and release their juices.
Stir in the garlic, paprika, oregano, salt, and black pepper. Cook for about 30 seconds, just until fragrant.
Add the dry orzo directly to the pan. Stir and cook for about 1 minute.
Pour in the chicken broth and stir well.
Return the chicken thighs to the pan. Bring the mixture to a gentle simmer, then cover and cook for about 12–15 minutes, stirring occasionally, until the orzo is nearly tender and the chicken is cooked through.
If there is still excess liquid, uncover the pan and continue cooking for another 2–5 minutes, stirring occasionally, until the orzo is tender and the mixture is creamy but not watery.
Stir in the baby spinach and cook just until wilted.
Turn off the heat. Stir in the lemon juice and crumbled feta.
Let the dish rest uncovered for 3–5 minutes before serving. The orzo will continue to absorb some of the sauce as it sits. Bon appétit!