Washington Post. They recommend kale of course. This is actually a twist on an ancient pasta recipe Pasta Alla Gricia, which is just pasta with crispy pork and greens. An important tip is to cook the pasta in no more than two quarts water, since that concentrates the starch in the water which is used later in the recipe.
Ingredients
Kosher salt, optional
1 pound spaghetti
1 tablespoon extra-virgin olive oil, with more for pasta
8 ounces bacon, guanciale or pancetta, cut into 3/4-inch cubes or strips
10 1/2 ounces curly kale, stems removed, chopped or torn into bite-size pieces (or, spinach)
1 cup (3 1/2 ounces) finely grated pecorino Romano cheese or Parmesan cheese
Freshly ground black pepper
Instructions
1. Bring a large pot filled with 2 quarts of water to a boil. Add salt, if desired. Cook the pasta in the boiling water for 7 minutes, about 4 minutes less than the package instructions indicate.
2. When the pasta is cooked, drain, reserving 1 1/2 cups of the cooking water. Immediately drizzle the drained pasta with olive oil. Use tongs or a wooden spoon to toss and coat the pasta with the oil.
3. Dry the pot with a kitchen towel and it set over medium heat. Add the 1 tablespoon of oil and heat until shimmering. Add the bacon and cook, stirring frequently, until the fat is mostly rendered, about 5 minutes. If bits of meat are sticking to the bottom of the pot, add a splash of pasta water and use a wooden spoon to loosen them.
4. Add the greens and cook, stirring, until it wilts and starts to brown in spots, 3 to 4 minutes.
5. Reduce the heat to low. Fluff the cooked pasta with a fork and then add it, the cheese and 1 cup of the reserved pasta water to the pot. Stir vigorously until the cheese melts and transforms into a creamy sauce that coats the pasta, 4 to 5 minutes. If the sauce is too thick or dry, add more pasta water, 2 tablespoons at a time, until it reaches the desired consistency. Taste and season with pepper, as desired.