Fill a large pot with water, add salt, and bring to a boil. Cook spaghetti or linguine according to package instructions until al dente, about 8 to 10 minutes. Reserve 1 cup of pasta water before draining.
In a large skillet, melt butter over medium heat. Add minced garlic and red pepper flakes, sauté for 1 minute until fragrant.
Add shrimp to the skillet, season with salt and pepper, and cook for 2 to 3 minutes on each side until pink and opaque.
Add the drained pasta to the skillet with shrimp. Pour in reserved pasta water, lemon zest, and lemon juice. Toss to combine and adjust seasoning to taste.
Serve hot, garnished with parsley and Parmesan cheese.
Notes
Use fresh shrimp for the best flavor. Adjust seasoning to your preference.