Cook the pasta according to package directions, drain reserving ½ cup pasta water. Set – aside.
While the pasta cooks heat the oil in a large skillet, add the bacon and cook until crisp. Remove and set aside.
To the oil, (add or remove to make about 3 tablespoons) add the onion, lower the heat and caramelize the onion until deep brown, about 10 – 15 minutes, stirring often. Remove and set aside.
Add the kale to the skillet and stir until it is well coated with the oil; add the garlic along with 1 cup water; stir; bring to a simmer, cover and cook for 5 – 6 minutes, or until tender, adding more water if necessary. When tender, add the pasta along with the bacon and onions, mix well. Season to taste with salt and freshly ground pepper, heat through, adding some of the pasta cooking liquid if it seems too dry. Spoon into warmed wide bowls and sprinkle with cheese, if desired.