From Puerto de Cotos' parking go north wards, left if you come from the tramway station, along a branch road. On the right side of Club Alpino and next to Casa Los Cotos raises a wooden stairway wich leads you to the trail.
Firstly the trail goes zigzaging through a fir wood. Soon lots of stakes guide you to a gravel steep stretch crossing a shrub field. In 25 minutes you'll be on the forest trail wich comes from the spot where once raised the altitude snack-bar of the ski resort (called Area 2.100 at about 2.080 m). Follow it to your left, it climbs softly the vast South face of Dos Hermanas Menor (2.268 m), if you wish you can take a short cut across the bush field because the trail zigzags a lot (better on descent because you can discern the trail). On this rounded mountain (50 min) remains the one-time Spanish Civil War entrenchment. Follow the hill range to the NE leaving aside Dos Hermanas Mayor (2.285 m). Then descend slightly to a col (2.259 m), to its right opens the cliff over Laguna Grande. Finally deal with a soft and large slope, first half a meadow marked out with big rock piles and second half a scree slope marked with little rock piles, to reach the summit (1h 30 min -1 h 45 min). At least 3 hours needed for climb and descent with good conditions of weather and no-snow.
Right Wood Variant
If you want to soften the first section of the path you can hike through another pine wood, the one to ther right of Casa Los Cotos, by a forest trail. At end of the first and long straight you'll run up against Fuente (drinking fountain) del Cubeiro on your left. After some bends you'll cross the old ski-run of La Pradera, wich comes from Area 2.100 (35 min). Then follow the forest trail as said.
Crampons can be necessary on some winter days. As well take warm clothes with you, anti-blizzard mask, map and compass.