Heat olive oil in a large skillet over medium-high heat. Add the sliced chicken sausage and cook until browned, about 4–5 minutes. Transfer to a plate and set aside.
In the same pan, add the chopped onion and a pinch of salt. Cook 3–4 minutes until translucent. Add garlic and cook 30 seconds until fragrant.
Add the orzo and stir for 1 minute to lightly toast for added flavor.
Pour in diced tomatoes with their juices and the chicken broth. Bring to a gentle boil, then reduce heat to medium-low. Cover and simmer 8–10 minutes, stirring occasionally, until orzo is tender.
Stir in the heavy cream and return the sausage to the pan. Add spinach, Parmesan, lemon zest, and juice. Cook 2–3 minutes until greens wilt and sauce is creamy.
Taste and adjust seasoning with salt and pepper. Garnish with chopped parsley and extra Parmesan. Serve warm with lemon wedges.
Notes
Use a wide skillet to allow even orzo cooking.
If the pan dries out before the orzo is cooked, add more broth a little at a time.
Store leftovers in an airtight container for up to 3 days; reheat with a splash of water or broth to loosen the sauce.