How to Make It
Snap off the ends of the asparagus. Cut the asparagus stems into 1/2-inch pieces, leaving the tips intact.
In a large pot of boiling, salted water, cook the spaghettini until almost done, about 5 minutes. Add the asparagus and cook until both are done, about 4 minutes longer. Drain.
Meanwhile, in a small frying pan, melt the butter over low heat. Cook, stirring, for 2 minutes. Add the walnuts and salt and cook, stirring, until the butter is golden brown, about 3 minutes longer. Add the garlic and cook for 20 seconds. Stir in the pepper. Toss with the pasta and asparagus and serve with Parmesan.
Toss the pasta with the other ingredients right in the original pasta-cooking pot. The pasta will stay hot, and you'll avoid dirtying a bowl.