Bring a 5- to 6-quart pot of water to a rolling boil. Add 1 tablespoon fine salt.

Add the fettuccine or linguine and cook according to the package directions until al dente, usually 9 to 11 minutes. Stir occasionally to keep the strands separated.

Before draining, scoop out 1 cup (240 ml) of the starchy pasta cooking water. Drain the pasta without rinsing.

While the pasta cooks, melt the butter in a 12-inch deep skillet over medium-low heat.

Add the minced garlic and cook for 30 to 45 seconds, stirring constantly. The garlic should smell fragrant while remaining pale rather than turning brown.

Pour in the vegetable broth and increase the heat to medium. Simmer for 3 to 4 minutes, until the liquid reduces slightly.

Reduce the heat to medium-low and pour in the heavy cream. Add the black pepper and 1/4 teaspoon salt. Bring the mixture to a gentle simmer and cook for 3 minutes.

Reduce the heat to low: Add the 1 1/2 cups (135 g) Parmesan in three additions, whisking until each portion melts before adding more. Do not let the sauce boil.

Whisk in 1/2 cup (120 ml) of the reserved pasta water. The sauce should look smooth and glossy and be loose enough to flow slowly from a spoon.

Transfer the drained pasta to the skillet: Toss gently with tongs for 1 to 2 minutes until every strand is coated.

Add more reserved pasta water a few tablespoons at a time if the sauce becomes too thick. If it looks too thin, toss the pasta over low heat for another minute.

Remove the skillet from the heat and stir in the lemon juice. Taste before adding additional salt because Parmesan is naturally salty.

Let the pasta stand for 5 minutes. The sauce will thicken slightly and cling more closely to the noodles.

Divide among six bowls and garnish with parsley, additional Parmesan, or crushed red pepper flakes if desired. Serve warm.