Cook the spaghetti or linguine according to package instructions in a large pot of salted boiling water until al dente. Reserve 1 cup of pasta water, then drain the pasta and set aside.

In a large skillet over medium heat, melt the butter. Add the minced garlic and red pepper flakes, cooking for about 1-2 minutes until fragrant, being careful not to burn the garlic.

Add the shrimp to the skillet, seasoning with salt and pepper. Cook for 2-3 minutes on each side until the shrimp turn pink and opaque.

Stir in the lemon zest and lemon juice, then add the drained pasta to the skillet. Toss everything together, adding reserved pasta water a little at a time until the desired sauce consistency is reached.

Remove from heat and stir in the chopped parsley. Adjust seasoning with additional salt and pepper if needed.

Serve immediately, topped with grated Parmesan cheese.