Cook the spaghetti in plenty of salted boiling water, observing the cooking time for al dente pasta. Drain and set aside.
In a saucepan, melt the butter in the oil and fry the onions for 5 minutes. Add in the tomato, saffron and white wine, and then let reduce over high heat for 5 minutes. Add the chorizo and clams.
Cover and cook for several minutes. Add in the cooked spaghetti, the tub of Boursin® Cuisine and let it warm over low heat.
Divide the mixture among 4 plates and sprinkle with chopped parsley.