Cabbage Spaghetti and Bacon

Cook the pasta until tender but still slightly firm, about 8 minutes. Reserve 1 cup of the pasta cooking water and set aside. Drain well and rinse in cold water until cool to stop the cooking process.
Cook the bacon in a large deep-sided skillet or Dutch oven over medium heat. Remove the bacon from the stove and crumble it. Leaving about 1 tablespoon of grease in the pot, return it to the stove.
Add the onion and cabbage to the bacon grease and stir to coat. Add about ¼ cup of pasta water and cover with a lid. Cook covered for 5 minutes. Uncover and continue cooking over medium-high heat, while stirring frequently, until the vegetables begin to soften and the liquid is absorbed. Season generously with salt, pepper, and red pepper flakes.
When the cabbage has softened, return the pasta and the bacon to the pot and toss well. Add a generous splash or two of the reserved pasta water, if the pasta looks dry. Sprinkle with Parmesan and parsley. Toss again. Taste and adjust the salt and pepper, as desired.