Dice the flesh of the pumpkin. Peel and chop finely the clove of garlic with half an onion and the leaves off the rosemary sprig. Fry lightly this chopped mixture in a large saucepan with oil. As soon as it goldens, add the diced pumpkin, mix with a wooden spoon and brown.Ladle the broth over the pumpkin, cover the pan with a lid and simmer over a low heat. After about 20 minutes season with just a touch of salt and a grind of pepper, add the capers (well rinsed and drained) and the stoned black olives, stir and simmer for another 10 minutes over a low heat.In the meantime cook the pasta al dente in a pan full of boiling salted water; drain it and pour it in the pan with the sauce, stirring well to fold in all the flavours and, if necessary, adding a couple of spoons of its cooking water. Sprinkle the pasta dish with the chopped parsley and basil mixture; arrange it in a serving dish and serve immediately.