Cook the penne in salted water. I find here fit very well those from spelt or wholemeal, but light penne also taste good.
Dice the onion and sauté in a little butter and olive oil until translucent. Add the raisins, pine nuts, saffron and Brussels sprouts (cut if necessary) and pour in the broth. Cook for about 5 min. or until thickened to desired consistency.
Mix with the pasta, remove from heat and let stand for approx. 5 min.