Step 1

Heat the oven to 400°. Snap the tough ends off the asparagus and discard them. Cut the spears into 1-inch pieces. Put the asparagus on a baking sheet and toss with the oil and 1/4 teaspoon each of the salt and pepper. Roast until tender, about 10 minutes.

Step 2

Meanwhile, put the vinegar in a small saucepan. Simmer until 3 tablespoons remain. Stir in the brown sugar and the remaining 1/4 teaspoon pepper. Remove from the heat.

Step 3

Cook the penne in a large pot of boiling, salted water until just done, about 13 minutes. Drain the pasta and toss with the butter, vinegar, asparagus, Parmesan, and the remaining 1 3/4 teaspoons salt. Serve with additional Parmesan.