01 - Bring a large pot of salted water to a boil. Cook the pasta until al dente according to package instructions. Reserve 1/2 cup of pasta cooking water and drain the pasta.
02 - Heat olive oil in a large skillet over medium-low heat. Add sliced garlic and sauté gently for 2 to 3 minutes until fragrant and just golden, avoiding browning.
03 - Optionally, stir in crushed red pepper flakes and cook for 30 seconds.
04 - Add drained pasta to the skillet with garlic oil. Toss to coat evenly, gradually adding reserved pasta water until the sauce lightly clings to the noodles.
05 - Season with salt and black pepper to taste. Remove from heat and stir in half the parsley and half the Parmesan cheese.
06 - Distribute pasta onto plates. Top with remaining parsley, Parmesan, and optional lemon zest. Serve immediately.