Add onion and mushrooms with a pinch of salt and pepper; sauté until softened, about 4 minutes.
Stir in garlic and thyme and cook until fragrant, about 1 minute.
Pour in chicken broth, half the lemon juice, and add orzo. Stir to combine.
Add cream and bring to a gentle boil. Reduce heat and simmer, stirring often, until orzo is tender and sauce thickens, about 10 minutes.
Turn heat to low. Stir in cooked chicken, parmesan, spinach, and remaining lemon juice. Cook until chicken is warmed through and spinach has wilted, adding splashes of broth as needed.
Season to taste with salt and pepper, and serve warm.
Notes
Use Cream such as half & half or heavy cream to reduce the risk of curdling when exposed to heat and lemon juice.
To make this gluten-free, substitute gluten-free orzo, short cut pasta, or rice and check your broth and parmesan for gluten-free certification.
Storage: Refrigerate leftovers in an airtight container for 3–4 days. Reheat gently, adding a splash of broth if needed.
Nutrition Information is an estimate only and will vary according to specific ingredients and amounts used.