Begin by cooking the spaghetti or linguine according to the package instructions in a large pot of salted boiling water. Cook until al dente, then drain and set aside, reserving 1/2 cup of pasta water.
In a large skillet over medium heat, melt the butter. Once melted, add the minced garlic and sauté for about 1-2 minutes until fragrant and lightly golden, being careful not to burn it.
Add the shrimp to the skillet in a single layer. Season with salt, pepper, and red pepper flakes if using. Cook for 2-3 minutes without stirring until the shrimp start turning pink.
Flip the shrimp and add the lemon zest and lemon juice to the skillet. Stir well and cook for another 2-3 minutes until the shrimp are fully cooked and opaque.
If the sauce is too thick, stir in a little of the reserved pasta water until you reach your desired consistency.
Add the cooked pasta to the skillet and toss everything together until the pasta is well coated in the garlic-lemon sauce. Mix in the chopped parsley and adjust the seasoning if necessary.
Serve hot, garnished with extra parsley and grated Parmesan cheese if desired.
Notes
Serve in a large pasta bowl garnished with fresh lemon slices and extra parsley for a pop of color.