In a large pot, bring salted water to a boil. Add the spaghetti or linguine and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta.
In the same pot or a large skillet, melt the unsalted butter over medium heat. Add the minced garlic and red pepper flakes, cooking for 1-2 minutes until the garlic becomes fragrant and slightly golden.
Add the cooked pasta to the skillet with the garlic butter. Toss to coat the pasta evenly with the buttery goodness. If the pasta seems dry, gradually add some reserved pasta water until it reaches a desired creamy consistency.
Add the grated Parmesan cheese, lemon zest, and lemon juice to the pasta. Toss again to combine everything. Season with salt and black pepper to taste.
Remove from heat and stir in the chopped fresh parsley for a bright flavor.
Notes
Serve with extra Parmesan and a lemon wedge for added flavor.