- 1 1/2 lb asparagus, ends trimmed, stalks and tips cut into 1" segments
- Kosher salt
- 1/4 lb bacon, finely sliced
- 8 green onions, finely sliced, whites and greens reserved separately
- 1 lb fettuccine or other noodle pasta
- 1 lemon, juiced and zested
- 3 Tbsp unsalted butter
- 3 Tbsp finely minced fresh flat-leaf parsley leaves
- Freshly ground pepper
- 1/2 cup finely grated Parmigiano-Reggiano, plus more for garnish
Bring a large pot of salted water to boil. Add asparagus and cook until just tender but still bright green, about 2 minutes. Transfer to an ice bath to chill. Dry carefully and set aside. Keep water on heat for pasta.
In a large frying pan over medium-high heat, add bacon. Cook until bacon is crisp and rendered, about 5 minutes. Add asparagus, increase heat to high, and cook, tossing and stirring frequently until lightly browned, about 2 minutes. Add green onion whites and cook, stirring constantly, until fragrant, about 30 seconds. Remove from heat and add 1 cup asparagus cooking water to pan.
Return asparagus water to a boil and add pasta. Cook according to package instructions until al dente. Drain, reserving 1 cup pasta water, and add to pot with bacon and asparagus. Do not return pot to heat. Add lemon juice and zest, butter, parsley, green onion greens, and black pepper. Stir until butter is melted. Add grated cheese and extra pasta water, stirring until desired consistency is reached. Season to taste with salt and more pepper.
Serve immediately, garnishing with shaved Parmigiano-Reggiano.