01 - Bring a large pot of salted water to a boil. Cook angel hair pasta according to package instructions until al dente. Reserve 1/2 cup pasta water before draining; set pasta aside.
02 - Pat shrimp dry and season lightly with salt and pepper.
03 - In a large skillet over medium-high heat, melt 2 tablespoons butter with olive oil. Add shrimp and cook 1-2 minutes per side, until just pink and opaque. Remove shrimp to a plate and cover loosely.
04 - Reduce heat to medium. Add remaining 2 tablespoons butter to the skillet. Stir in garlic and cook for 30 seconds, until fragrant (do not brown).
05 - Add lemon zest, juice, and red pepper flakes, scraping any browned bits from the pan.
06 - Return shrimp to the skillet. Add drained pasta and half the parsley. Toss well to combine, adding reserved pasta water as needed to create a silky sauce.
07 - Season with additional salt and pepper to taste. Serve immediately, garnished with remaining parsley, lemon wedges, and Parmesan if desired.