Spaghetti with Olive, Caper and Anchovy Sauce

1 can Crown Prince Anchovies, drained and finely minced

1/3 cup olive oil

2 onions, finely chopped

3 cloves garlic, minced

1/2 teaspoon chili flakes, or to taste

6 large ripe tomatoes, diced

1 3.5 ounce jar of capers in brine, drained and rinsed

1 15 ounce can pitted black olives, drained and sliced

3 tablespoons chopped fresh parsley

16 ounces spaghetti, cooked according to package directions

salt and black pepper to taste