Cook pasta al dente according to the directions and save ½ cup pasta water.
Cut bacon into thin strips then add to a heavy bottomed skillet and cook over medium-medium-low heat for 15 minutes.
Once its mostly crispy, remove it and place it in a paper towel-lined bowl. Pour out half the bacon grease and set it aside so that there’s about 2-3 tbsp remaining.
Add onion and a pinch of salt and cook for 5 minutes.
Add garlic and red pepper flakes and cook for another 3 minutes.
Stir in the tomatoes, water, and a pinch of salt. Then stir in half of the crispy bacon and put the lid on the pot and simmer for 30 minutes.
Once the sauce is done, stir in ½ cup of cheese and season with salt and pepper if needed.
Toss with al dente pasta into the sauce. If it looks dry, add in pasta water, little by little, until the sauce coats each noodle.
Top with remaining cheese and bacon before serving.