01 - Cook the pasta in a large pot of salted boiling water according to package instructions until al dente. Reserve 1/2 cup pasta water, then drain and set aside.
02 - Pat shrimp dry with paper towels. Season lightly with salt and pepper.
03 - In a large skillet over medium-high heat, heat 1 tbsp butter and the olive oil. Add shrimp in a single layer and cook for 1–2 minutes per side until pink and opaque. Transfer shrimp to a plate and set aside.
04 - Reduce heat to medium. Add remaining 3 tbsp butter to the skillet along with the garlic and red pepper flakes. Sauté for 1 minute until fragrant (do not brown garlic).
05 - Add the lemon zest, lemon juice, and white wine (or broth), scraping up any browned bits from the pan. Simmer for 2 minutes to reduce slightly.
06 - Return shrimp (and juices) to the skillet. Add drained pasta and toss to coat, adding reserved pasta water a little at a time until the sauce is silky and clings to the pasta.
07 - Remove from heat. Stir in chopped parsley. Adjust seasoning with salt and pepper as needed. Serve immediately with lemon wedges and grated Parmesan if desired.