Bring a large pot of salted water to a boil over high heat. Add the orzo and cook according to package instructions, usually about 8-10 minutes, until al dente. Drain and reserve ½ cup of the starchy pasta water.

In a large skillet, melt 2 tablespoons of butter over medium heat. Add the shrimp in a single layer and sauté for about 2-3 minutes on each side, until they turn pink and opaque. Remove from the pan and set aside.

In the same skillet, add another tablespoon of butter if needed and reduce the heat to medium-low. Add the minced garlic and sauté for about 30 seconds until fragrant.

Return the shrimp to the skillet and add the drained orzo, fresh spinach, and reserved pasta water. Toss for about 2-3 minutes until the spinach wilts and the mixture is creamy.

Off the heat, stir in the lemon zest and grated Parmesan, mixing until creamy and well combined. Serve hot, garnished with extra Parmesan or fresh herbs if desired.