01 - Pat the shrimp thoroughly dry with paper towels and season generously with salt and freshly ground black pepper. Melt 1 tablespoon of butter in a large sauté pan over medium-high heat. Arrange the shrimp in a single layer and sear for 1 to 2 minutes per side until they turn pink and are just cooked through. Transfer to a plate and tent loosely to keep warm.
02 - Add the remaining butter to the same pan. Sauté the chopped onion for 2 to 3 minutes, stirring occasionally, until softened and translucent. Add the minced garlic and cook for 30 seconds until fragrant, being careful not to let it brown.
03 - Stir the orzo into the pan and toast for 1 to 2 minutes, tossing constantly, until lightly golden. Pour in the white wine and stir until it fully evaporates.
04 - Pour in the broth half a cup at a time, stirring frequently. Allow each addition to be mostly absorbed by the orzo before adding the next. Continue this process for 10 to 12 minutes until the orzo is tender and the mixture is creamy.
05 - Stir in the heavy cream and grated Parmesan cheese, mixing until the sauce is smooth and well combined. Fold in the baby spinach and cook for about 1 minute until wilted.
06 - Return the seared shrimp to the pan along with the lemon zest, lemon juice, chopped parsley, and crushed red pepper flakes. Gently toss everything together until heated through. Taste and adjust salt and pepper as needed. Serve immediately, garnished with additional parsley and lemon wedges.