Heat olive oil in a large deep skillet or pot over medium-high heat.
Season the chicken pieces with salt, black pepper, garlic powder, and dried oregano.
Add the chicken to the skillet and cook for 5-6 minutes until browned and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the chopped onion and cook for 3-4 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Add the orzo pasta to the skillet and stir to coat with the oil and onion mixture.
Pour in the chicken broth and 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.
Stir in the heavy cream, grated Parmesan cheese, lemon zest, and lemon juice.
Add the cooked chicken back to the skillet along with the fresh baby spinach.
Cook for an additional 2-3 minutes, stirring gently, until the spinach is wilted and the sauce is creamy.
Remove from heat and stir in the chopped fresh parsley.
Serve immediately, garnished with extra Parmesan if desired.