Bring a large pot of lightly salted water to a boil; cook pasta at a boil until tender yet firm to the bite, about 8 minutes. Drain.

Meanwhile, cook bacon in a large deep skillet until crisp. Drain on paper towels; cut or break into 1/2-inch pieces. Discard bacon drippings.

Heat oil in the same skillet over medium heat. Add onions; cook, stirring occasionally, 5 minutes. Add bell pepper, parsley, garlic, and pepper flakes; cook 2 minutes. Add tomatoes and chopped bacon; simmer 10 minutes, stirring occasionally. Stir in olives, capers, and oregano; simmer 2 minutes. Taste; season with salt if desired.

Toss pasta with sauce and 1/2 cup Parmesan cheese. Sprinkle servings with cheese.