From Turin, drive north towards Lanzo, but before you reach this town you have to turn towards the Val di Viu' (the more southern of the three Valli di Lanzo).
Drive to the end of the road (open only without snow), up to the power plant dam, and reach the Malciaussia lake (1805m, 5922ft)

Route Description

First day

Walk to the beginning of the lake, keeping it on the left, then cross the stream, and, at the junction, forget the 111 trail on the right hand (the one to refuge Tazzetti), to take the GTA trail on the left.
After 200m height difference there is the crossroads to Lago Nero and to Colle (=pass) della Croce di Ferro: you have to take this last one (even if the Lago Nero is worthy a little deviation).
From here the path is almost clearly marked up to the pass (Colle della Croce di Ferro, 2558m, 8392ft), that connects the Val di Viu' with tha Susa Valley. You have Mt Palon (2965m, 9728ft) on your right.
Shortly after the pass there is an unattended refuge, where you can stop for lunch.
The trail continues at constant altitude up to a cross road: you have to keep on the right, laying aside the main GTA trail, and continuing almost at constant altitude: the trail becomes less marked, and more difficult in some points, when crossing some thaw water streams...
You cross the small Passo della Capra (2456m, 8058ft), from which sometimes it is possible to see some kites, then continue crossing other three streams, and the trail begins to raise up to connect to the 558 trail from La Riposa refuge to the Ca' d'Asti refuge (very close to this one).
Here (2854m, 9364ft) you can have dinner and spend the night.

Second day

Heading North, you start to climb the "normal" trail (well marked) up to La Crocetta (a small iron cross, with a flat area where to rest, at 3306m, 10846ft), then continue for the last section up to the summit (3538m, 11608ft), where, in case of emergency, there is a bivouac. Pay attention to this section: there are some fixed ropes, but the trail is insidious, and the precipice on your right is very steep.
After the well deserved resting and - hopefully - breath-taking view of the Alps (you can see the Monviso towards South), You start the descent on the NW ridge. At a certain point, before the residual of the ephemeral lake on the side of the glacier, turn right and cross the glacier in NE direction. The path is not visible, except if there is some fresh snow and someone else has trekked on it before, so it is better to have good visibility on the glacier, heading to the ice tongue at the E border of the glacier, as seen on the map and marked in this picture: here you can find the Col della Resta. Pay attention, the passage between the glacier and descent is narrow and steep.
After an initial steep zig-zag, the trail becomes smoother, and, following the signs, it developes on the left of a ridge, and arrives (with a short final steep descent, crossing the ridge itself on the right) to refuge Tazzetti, where it is possible to have a nice break.
From here it is only a quiet downwards walk (about 2 hr) to the Malciaussia lake

Essential Gear

Normal hiking gear (taking into account for the cold weather at altitude), no need for crampons, even on the glacier (expected you attempt it in summer season). Remember sunglasses, windstopper jackets, and a compass could be useful on the glacier, in case of fog

Miscellaneous Info

unlike most of the trek descriptions, we preferred to have a "clockwise" ring, because it is more balanced across the two days.
The counterpart is to spend the night (and the dinner), at the refuge Ca' d'Asti, in my opinion qualitatively worse than the Tazzetti one.