Slice 1 pound of bacon into small pieces. If you're watching your fat, you can trim the fatty bits off, but I think that's a waste of deliciousness. A good smokey bacon works best, but avoid anything weird like maple-flavored. Saute for several minutes, until you've rendered the fat out of the bacon. Drain off the fat, then add 1/2 an onion, diced, and saute until the onion is translucent. You're not trying to make the bacon crispy, it just needs to be cooked. Add 3 cans of diced tomatoes, well drained, 1 Tblsp Italian seasoning and 1/2 tsp of red pepper flakes (optional). Cook until the tomatoes form a sauce.
Serve over freshly cooked spaghetti and top with grated cheese.