Go around Louvie Lake on the right bank (meaning the left of your hiking direction). At the other end of the lake, head in an almost constant north direction (S).
Keep following this trail regularly waymarked White Red White (Blanc Rouge Blanc BRB). Once you reach high point 2418, you'll find a path leading to Plan da Gole (1) to the right. Ignore it and start heading west. You'll reach another crossing at high point 2628 (2), meeting up with a trail coming from Termin pass and another called Chamonix-Zermatt Walker's route.
Take it to the right, it joins up with the path called Alpenpässe-Weg which you've been following since Louvie. Gradually head north-east within a mineral landscape, passing in front of Petit Mont-Fort Lake (3) before finishing the climb at Louvie Pass (4).
Start the hike down rapidly spotting the Grand Désert glacier to the right, head east, crossing the glacial lakes (5) forged by the glacier and start a short climb up to Prafleuri Pass. Reach the pass, which at an altitude of 2987 m is the highlight of the day (6).
Next, head east, then south, then south-east and after a long hike down you'll reach a meadow below Prafleuri Hut (7).
Start the last, short but steep climb to the hut (E) to end the day.