In a small skillet cook the garlic, the onion, and salt and pepper to taste in the oil over moderately low heat, stirring, until the onion is soft, add the tomatoes and the broth, and simmer the mixture until the liquid is reduced by about one third. Stir in the olives, the parsley, and salt and pepper to taste and keep the mixture warm. In a kettle of boiling salted water cook the pasta until it is al dente and drain it well, reserving 1/3 cup of the cooking water. In a serving bowl whisk 3 ounces of the goat cheese with the reserved cooking water until the cheese is melted and the mixture the smooth, add the pasta and the tomato mixture, and toss the mixture well. Sprinkle the pasta with the additional goat cheese.