Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve 1/2 cup of pasta water before draining.
In a large skillet over medium heat, melt the butter. Add the minced garlic and sauté for about 1 minute until fragrant, being careful not to burn it.
Stir in the lemon zest, lemon juice, and red pepper flakes (if using). Let it simmer for a minute to combine the flavors.
Add the drained pasta to the skillet and toss to coat in the sauce. Gradually add the reserved pasta water, a little at a time, until the sauce reaches your desired consistency.
Stir in the Parmesan cheese and season with salt and black pepper. Toss everything together until well combined.
Remove from heat and sprinkle with fresh parsley before serving. Enjoy warm!
