Or other greens. Or other pasta. The cooking time will depend on the type of greens and/or pasta. Taste for doneness.

7 c or so chopped bok choi, stems and leaves kept separate
6 or slices bacon, chopped
1 onion, sliced in thin half moons
2 garlic cloves, peeled and minced, or to taste
salt, for pasta water, to taste
1 lb penne or other pasta
1 c grated Romano, Parmesan or Asiago cheese, or other grated cheese, plus extra
salt and pepper, to taste

1. Bring a big pot of water to the boil. Don’t salt it yet. Toss in the choi stems. Cook until just tender, about 4 minutes (this will depend on the size of the choi–younger, smaller choi will cook faster than larger, more mature choi). Add leaves and cook for another minute or so. With a slotted spoon or tongs, transfer choi to a colander. If the choi do not come out easily you can just drain the pot into the colander and start boiling another pot of water. Rinse the choi with cold water to stop the cooking (or not), allow to drain and set aside. Bring the water back to the boil for the pasta.

2. Cook bacon over moderate heat in a large skillet, large enough to hold the cooked pasta and choi. When the bacon is staring to crispen, turn down the heat some and add the onion. Cook, stirring frequently, until the onion begins to turn golden. If it looks like it’s starting to blacken or burn, turn the heat down. Add the garlic and cook, stirring, for another couple of minutes.

3. When the onion is in the skillet, add 2 or 3 T of salt to the boiling water and add the pasta. Cook until al dente, or to your preference. Reserve 1 cup of the pasta water, then drain the pasta.

4. Add the reserved pasta water to the skillet. Stir, scraping up any brown bits (the fond) on the bottom of the skillet. Add the choi, stirring to combine. Add the pasta, in two or three batches, stirring well after each addition. Add cheese, salt, and pepper, stirring, until combined and heated through. Serve with extra cheese, if desired.