Crisp-tender asparagus, bright lemon zest and juice, rich mascarpone, and salty Pecorino Romano make a sensational sauce for this one-pot pasta dish. Grated hard-cooked egg yolks add extra oomph.
Bring a large pot of generously salted water to a boil. Add asparagus and cook until crisp-tender and bright green, 2 to 3 minutes. Transfer to a plate with a slotted spoon. Add pasta to water; cook according to package instructions until al dente. Drain, reserving 1 1/2 cups pasta water. Return pasta to pot with asparagus. Stir in zest and juice and both cheeses; toss to coat. Add pasta water, little by little, to adjust consistency until creamy. Sprinkle with grated yolks and pepper; serve.
To hard-cook eggs, cover them in a medium saucepan with one inch of water and bring to a boil, then remove from heat and cover for 10 minutes. Drain and transfer to an ice-water bath.