01 - Bring a large pot of salted water to a boil. Cook pasta until al dente following package directions. Reserve ½ cup pasta water and drain pasta.
02 - Pat shrimp dry and season with kosher salt and black pepper.
03 - Heat olive oil in a large skillet over medium-high heat. Cook shrimp 1 to 2 minutes per side until opaque and lightly golden. Remove shrimp and set aside.
04 - In the same skillet, add minced garlic and crushed red pepper flakes if using. Sauté for 30 seconds until fragrant.
05 - Add fresh spinach and cook, stirring, until just wilted, about 1 minute.
06 - Add lemon zest, juice, and broth to the skillet. Simmer for 1 minute, scraping up any browned bits.
07 - Reduce heat to low. Stir in unsalted butter until melted.
08 - Add drained pasta and cooked shrimp to the skillet. Toss to combine, adding reserved pasta water as needed to achieve a silky sauce consistency.
09 - Stir in grated Parmesan cheese. Adjust seasoning with salt, pepper, or additional lemon juice as desired.
10 - Plate immediately, garnished with chopped parsley, extra Parmesan, and lemon wedges.