Bring a large pot of salted water to a rolling boil over high heat. Add 8 ounces of spaghetti and cook according to package instructions, typically for about 8-10 minutes, until al dente. Reserve 1 cup of starchy cooking water before draining the pasta.

In a large skillet, melt 4 tablespoons of unsalted butter over medium heat until it becomes foamy. Reduce heat to low and add the zest of 1 lemon along with 3 minced garlic cloves. Cook for 1-2 minutes, stirring frequently, until the garlic becomes fragrant and just starts to turn golden.

Using tongs, transfer the drained spaghetti directly into the skillet with the butter and garlic mixture. Immediately add ½ cup of the reserved pasta water to the skillet. Toss the spaghetti vigorously for about 1-2 minutes, ensuring the pasta is evenly coated.

Sprinkle in ½ cup of grated Parmesan cheese and continue to toss until the cheese melts and the sauce envelops the pasta smoothly. Squeeze in the juice of 1 lemon, stirring well to combine all flavors. Cook for an additional 1-2 minutes to let the sauce come together.

Taste the lemon pasta and season generously with sea salt and freshly ground black pepper. If desired, add more lemon juice for extra brightness. Garnish with additional lemon zest and a sprinkle of fresh parsley or basil before serving.