You'll get to Burgeis - the principal trailhead via SS38 ans SS40 from the south or S40 from Reschenpass in the north. In both cases just follow the Vinschgau / Val Venosta Valley. From Burgeis turn west onto a little side road towards Schlinig / Slingia wher the ascent starts.
Altitude gain: 850m
Trailhead: Schlinig / Slingia
From Schlinig there are two trails which lead to Sesvenna hut. One follows the road, the other (which I would recommend) runs along an old pilgrimage trail along the norhern slopes of the Schlinig Valley. At Inn Alm the both trails recombine and head for Sesvenna hut.
Shortly before you reach the hut, a trail (no 8) turns off to the right. It ascends along the slopes and later divides into two trails. Take the left one (still no 8), the right one (8A) leads back to Plantapatsch hut. The former trail heads up to Oberdörferjoch (2338m) where you turn right onto trail no 9 towards Pfaffensee. You'll reach the Watles summit ridge to its southwest and follow it to the top.
We did this route as a descent route and as such it was rather boring and cumbersome. We had to hike back all the way from Schlinig to Burgeis which was not very much fun.
Hiking gear is sufficient.