Pat the chicken thighs dry with paper towels and cut into bite-sized pieces. In a bowl, toss the chicken with cornstarch, garlic powder, onion powder, paprika, oregano, salt, and black pepper until evenly coated.

Heat olive oil in a large deep skillet over medium-high heat. Add the seasoned chicken and cook for 8-12 minutes, stirring occasionally, until browned and cooked through to an internal temperature of 165ºF (74ºC). Remove the chicken from the skillet and set aside.

Stir in the dry orzo, then pour in the chicken broth, scraping the bottom of the pan to deglaze if needed. Bring to a boil. Reduce heat to medium-low, cover, and simmer for 8–10 minutes, stirring occasionally, until the orzo is tender and most of the liquid is absorbed.

Reduce the heat to low and stir in the chopped spinach and Parmesan. Let the spinach wilt and the cheese melt into the orzo, about 2 minutes. Remove the skillet from the heat.

Add the lemon zest, lemon juice (about 2–3 tablespoons, to taste), and return the cooked chicken to the pan. Stir gently to combine.

Taste and adjust salt or lemon to preference. Serve warm, garnished with lemon slices, extra Parmesan, or black pepper.