01 - Bring a large pot of salted water to a rolling boil. Add spaghetti or linguine and cook according to package directions until al dente. Before draining, reserve 1/2 cup of the starchy cooking water. Drain pasta thoroughly.
02 - In a large skillet over medium heat, combine olive oil and butter. Once butter melts and begins to foam, add minced garlic. Sauté for 1 to 2 minutes until fragrant and lightly golden, taking care not to brown. Stir in red pepper flakes and lemon zest to infuse the flavors.
03 - Transfer the drained pasta directly into the skillet with the garlic butter sauce. Using tongs, toss vigorously to coat every strand evenly. Add small amounts of the reserved pasta water as needed to achieve a silky, emulsified consistency that clings to the noodles.
04 - Pour in fresh lemon juice and sprinkle half the Parmesan cheese over the pasta. Continue tossing until the cheese begins to melt and coat the noodles. Season generously with salt and freshly ground black pepper, adjusting to your preference.
05 - Divide the pasta among four warmed plates. Sprinkle the remaining Parmesan cheese over each serving and finish with a generous scattering of fresh parsley. Serve immediately while hot and aromatic.