- 4 ounces sliced bacon, cut crosswise into 1/2-inch pieces
- 2 tablespoons extra-virgin olive oil
- 1 medium onion, finely chopped
- 1 1/2 pounds asparagus, trimmed and cut on a long diagonal into 1/2-inch-thick slices
- 1 pound fusilli (short corkscrew pasta)
- 1/2 cup finely grated Parmigiano-Reggiano plus additional for serving
- Cook bacon in a 12-inch heavy skillet over moderately high heat, stirring occasionally, until browned and crisp, about 6 minutes. Transfer bacon with a slotted spoon to paper towels to drain. Pour off all but 2 tablespoons fat from skillet, then add oil and onion to skillet and cook, stirring occasionally, until onion is golden, about 4 minutes.
- Add asparagus and saute, stirring, until crisp-tender, 4 to 5 minutes. Season with salt and pepper.
- While onion is cooking, cook pasta in a 6- to 8-quart pot of until al dente. Reserve 1 cup pasta cooking water and drain pasta in a colander.
- Return pasta to pot along with asparagus mixture, 1/2 cup pasta cooking water, and cheese. Add remaining 1/2 cup cooking water to skillet and deglaze by boiling, stirring and scraping up brown bits, 1 minute. Add to pasta and toss over moderately low heat until combined well, about 30 seconds.
- Serve pasta sprinkled with bacon and with additional cheese on the side.