- 3 tablespoons olive oil
- 1 cup chopped onions
- 3 cloves garlic, minced
- 2 anchovy fillets, chopped (optional)
- 1/2 teaspoon red pepper flakes
- 1 (26-ounce) jar tomato basil sauce
- 1 (6-ounce) can pitted black or green olives, roughly chopped
- 1 tablespoon capers, rinsed and chopped
- 3 tablespoons chopped fresh parsley
- Balsamic vinegar, to taste
- 1 pound spaghetti
- Salt and pepper, to taste
- Grated Parmesan cheese, for serving (optional)
Heat oil in a heavy saucepan over medium-high heat. Add onions and cook until soft and translucent, 5 to 7 minutes. Stir in garlic, anchovies and red pepper flakes; cook until fragrant, about 3 minutes.
Add tomatoes, olives and capers to the pan. Bring to a simmer and cook until sauce has reduced slightly, stirring often, about 20 minutes. Stir in parsley and balsamic vinegar; season to taste with salt and pepper.
Bring a large pot of salted water to a boil. Cook spaghetti until al dente, according to package directions. Drain and toss with sauce. Serve with grated cheese.