Bring a large pot of salted water to a boil and blanch the kale for 2 min then drain the kale without discarding the water. Re-use the water to boil the pasta, then again to add back to the kale.
In a separate sauté pan, render all the fat from the bacon cubes and save for another use. Leave just enough for the dish. Remove the bacon cubes, cut in small pieces and set aside.
In the remaining fat, sauté the onion and garlic until soft and brown. Add the kale with a couple of ladles of liquid from the pasta pot and cover. Add 2 small bay leaves, thyme, and salt. Let cook for about 30 min until most of the liquid has evaporated and the kale is tender.
When done, add the pasta with the bacon cubes. Toss and serve.