Cook diced bacon in a large saucepan over medium high heat until crisp, about 5 minutes. Drain all but 2 tablespoons of drippings from the pan.
Add onions, and cook over medium heat about 3 minutes. Stir in garlic and red pepper flakes; cook 30 seconds. Add canned tomatoes, undrained; simmer 10 minutes, breaking up tomatoes.
Meanwhile, cook the pasta in a large pot of 4 quarts boiling salted water until al dente. Drain.
Stir basil into the sauce, and then toss with cooked pasta. Serve with grated Parmesan cheese.
