Step 1

In a large pot, bring 4 quarts water to a boil. Stir in the pasta and 1 tablespoon salt and cook, stirring occasionally, until just shy of al dente. Reserve about ½ cup of the cooking water, then drain.

Step 2

In the same pot over medium-high, melt the butter. Add the asparagus and ½ teaspoon salt, then cook, stirring often, until tender-crisp, 2 to 4 minutes. Add the garlic and cook, stirring, until fragrant, about 30 seconds. Add the pasta and the half-and-half, then bring to a simmer. Reduce to medium and cook, stirring, until most of the liquid has been absorbed and the pasta is al dente, 2 to 4 minutes.

Step 3

Off heat, stir in the Parmesan and lemon zest and juice; add reserved pasta water as needed so the sauce is silky and clings to the noodles. Stir in the chives, then taste and season with salt and pepper. Serve sprinkled with additional cheese.