Prep the lemon and garlic. Zest both lemons first, then juice them. You’ll want about 1/4 cup of juice. Mince or grate the garlic so it melts into the sauce.

Boil the pasta. Bring a large pot of well-salted water to a rolling boil. Add the linguine and cook until just shy of al dente, stirring occasionally. Reserve at least 1 cup of pasta water before draining.

Start the sauce base. In a large skillet over low heat, warm the olive oil. Add the garlic and cook gently for 30–60 seconds until fragrant, not browned. Add a pinch of red pepper flakes if using.

Build the lemon-butter emulsion. Add half the butter to the skillet and swirl until just melted. Pour in 1/2 cup of hot pasta water and whisk or swirl to combine, forming a thin, glossy sauce. Stir in the lemon zest and half the lemon juice.

Toss with pasta. Add the drained linguine straight to the skillet. Toss vigorously over low heat, adding the remaining butter a few pieces at a time until it melts and the sauce starts clinging to the noodles.

Finish with cheese and adjust. Sprinkle in most of the Parmesan and toss to melt. Add more pasta water, a splash at a time, to keep the sauce silky. Taste and add more lemon juice, salt, or pepper as needed.

Plate and garnish. Serve immediately with extra Parmesan, a drizzle of olive oil, and chopped parsley or basil. A twist of black pepper on top is a nice touch.