01 - Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve 1/2 cup pasta water, then drain.
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 turning golden, avoiding burning.
03 - Stir in red pepper flakes, if using, and cook for an additional 15 seconds.
04 - Add the drained pasta to the skillet and toss to coat in the garlic oil. Gradually add reserved pasta water until the sauce lightly coats the pasta.
05 - Season with sea salt and freshly ground black pepper. Remove from heat and toss in chopped parsley.
06 - Divide onto plates and top with grated Parmesan and a sprinkle of lemon zest, if desired. Serve immediately.