Step 1

Cook pasta in a large pot of boiling salted water, stirring occasionally, until al dente. Drain pasta, reserving 1½ cups pasta cooking liquid.

Step 2

Meanwhile, heat oil in a large Dutch oven or other heavy pot over medium-high until shimmering. Add asparagus, season with salt, and cook, stirring often, until just beginning to take on color, about 1 minute. Add garlic, lemon zest, and red pepper flakes and cook, stirring, until fragrant, about 30 seconds. Remove from heat and let sit until pasta is done.

Step 3

Add pasta and basil to pot with asparagus mixture and return to medium-high heat. Squeeze juice from both lemons into pot and add 2 oz. Parmesan and 1 cup reserved pasta cooking liquid. Cook, tossing vigorously and adding more pasta cooking liquid if needed, until sauce is creamy and emulsified and pasta is coated, about 1 minute. Taste and season with more salt if needed. Remove and discard garlic.

Step 4

Divide pasta among bowls, placing a lemon strip in each, and top with more Parmesan.