In my opinion the best way to do Cooks Cairn even with new windfarm. There is a tricky river crossing. Ok in dry weather but best to take sturdy bin bags in case..
There is a new car park under construction at Aldivalloch thanks to EDF . The company that constructed the new windfarm.
From here head west up an obvious grass track which becomes a proper track higher up. Head over the lovely named Dead Wife’s Hillock and down to the Blackwater burn. The road fords here but is quite deep at this point. Best to head upstream slightly and with the use of poles use stepping stones. I would recommend bin bags in case. It is a large burn.
From here keep on the track heading uphill between the wind turbines. Once you reach the beallach turn right and head uphill on an easy gradient to reach the Cairn. The views all round are superb.
Best to retrace your steps to return to the starting point.
9 miles in total this is a fab walk.