Season the chicken: Pat the chicken dry and season with 1/2 teaspoon salt, 1/4 teaspoon pepper, and the Italian seasoning.
Sear the chicken: Heat 1 tablespoon olive oil and the butter in a large deep skillet or Dutch oven over medium-high heat. Add the chicken in a single layer and cook 4–6 minutes, stirring once or twice, until lightly browned and just cooked through.
Transfer to a plate and keep warm.
Sauté the aromatics: Reduce heat to medium. Add the remaining 1 tablespoon olive oil. Stir in onion and a pinch of salt.
Cook 3–4 minutes until translucent. Add garlic and red pepper flakes; cook 30 seconds until fragrant.
Toast the orzo: Add the dry orzo to the pan. Stir to coat in the oil and aromatics and toast for 1–2 minutes until slightly golden.
This adds flavor and helps the orzo keep its shape.
Simmer with broth: Pour in the chicken broth and remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Bring to a gentle boil, then reduce to a simmer. Cook 8–10 minutes, stirring occasionally to prevent sticking, until the orzo is tender and the liquid has mostly absorbed.
Add cream and cheese: Lower the heat.
Stir in the cream, Parmesan, and lemon zest. The sauce will turn silky and slightly thick. If it looks too tight, splash in a bit more broth or water.
Finish with chicken and spinach: Return the chicken and its juices to the pan.
Add the lemon juice and fold in the spinach by handfuls until wilted, 1–2 minutes. Taste and adjust salt, pepper, and lemon to your liking.
Serve: Sprinkle with parsley if using. Serve warm with extra Parmesan and lemon wedges.
A drizzle of olive oil on top is a nice touch.