- ¾ pound asparagus
- ½ medium yellow onion
- 3 tablespoons butter
- 4 ounces prosciutto, sliced 1/8 inch thick
- Salt
- Freshly ground black pepper
- 2/3 cup heavy cream
- 1/3 cup freshly grated Parmigiano-Reggiano
- 1 pound penne (short fusilli or egg fettuccine are also good)
- Fill a pot for the pasta with about 6 quarts of water, place over high heat, and bring to a boil.
- Fill a 10-inch skillet (or asparagus cooker) with water, place over high heat, and bring to a boil.
- Cut off the white, woody bottom part of the asparagus spears, then peel the remaining bottom third. Add 1 teaspoon salt to the boiling water, then gently slide in the asparagus. Cook until the asparagus is tender, 5 to 6 minutes, then lift it out and set aside. Save ½ cup of the water the asparagus cooked in.
- While the asparagus is cooking, peel and finely chop the onion. Put the butter in a 12-inch skillet, add the chopped onion, and place over medium-high heat. Sauté until the onion has turned a rich golden color, about 5 minutes.
- Cut the prosciutto slices into strips about 1/8 inch wide and 1 inch long. When the onion is ready, add the prosciutto and saute until it loses its raw color, 1 to 2 minutes.
- Cut the asparagus into 1-inch lengths and add them to the pan. Continue sautéing until the asparagus becomes lightly colored, 2 to 3 minutes. Add the saved asparagus water and continue cooking until the liquid has evaporated completely, loosening any browned bits on the bottom of the skillet.
- Add about 2 tablespoons salt to the boiling pasta water, add the penne, and stir well. Cook until al dente.
- While the pasta is cooking, add the cream to the asparagus and cook until the cream has thickened, 1 to 2 minutes. Remove the pan from the heat.
- When the pasta is done, drain well, toss with the sauce and the freshly grated Parmigiano-Reggiano, and serve at once.