Heat the olive oil and butter in a large skillet over medium heat.
Add the finely chopped onion and cook for 3–4 minutes, stirring occasionally, until softened.
Stir in the minced garlic and cook for about 30 seconds, just until fragrant.
Add the uncooked orzo and stir continuously for about 1 minute, allowing it to become lightly toasted.
Pour in the broth and season with salt and freshly ground black pepper.
Bring the mixture to a gentle boil. Reduce the heat, cover the skillet, and cook for approximately 8 minutes, stirring occasionally so the orzo does not stick.
Add the shrimp and Italian seasoning. Stir gently to distribute the shrimp throughout the orzo.
Cover and continue cooking for 3–4 minutes, or until the shrimp are opaque and cooked through and the orzo is tender.
Reduce the heat and stir in the lemon zest, lemon juice, Parmesan, and baby spinach.
Gently mix until the cheese melts, the spinach wilts, and the Lemon Garlic Shrimp Orzo becomes creamy.
Sprinkle with chopped fresh parsley and serve warm. Add an extra squeeze of fresh lemon juice if desired.