From memory we borrowed Chockstoner robb's Bregaglia guide, I think it was Alpine Club. The North Ridge was a terrific climb and a good choice to do before tackling the harder Cassin Route (and it gets you to the top of the mountain!) But you'd probably need 2.5 days car-to-car.
The route-finding was quite straightforward. The ridge proper is gained from the L. Stay on it all the way to the summit. We detoured L I think a bit below where the Cassin tops out but that was a mistake - we had to climb a cruxy (5c?) pitch to get back on top. Mike pulled a big rock out of that pitch which missed me by a whisker but the rock up on the ridge is excellent. (Mike did a similar trick on the Dent du Geant a little later but that time I had to crawl off the mountain - long story!)
The cozy bivy hut on top slept 6. We had it to ourselves as most people head down to the refugio on the Italian side. But the word was that ice gear was necessary to walk back (clockwise around the mountain) to the Swiss hut. Abseiling back down the ridge was a long day but, hey, what a beautiful place.