Graswangtal at the road between Linderhof and Ammerwald. You can paark between the avalanche gate and the sign "Grenze 1km" at the roadside. You miight have spotted the steep cwm already. Most times there are some cars parked there (directly after the sign "Grenze 1km").
After parking your car you cross the guardrail and descend (already in split-mode) a few meters down to the stream bed (Neualpgris) and cross the stream at an appropriate spot. Now you can already see the middle-steep cwm (foothill of Hochgrieskar) and you can start to hike up, in the beginning through sparse forest till you reach a forest clearing. You follow the clearing until just before a prominent rock face (1500m). Here you turn to the right (West) to the wonderful steep slope of your later descent.
It goes up with many kick-turns till you reach the end of the cwm. About 50 meters before the end you exit the cwm to the right to a col and then left along the alpine-pine covered ridge steep on to Schwarzköpfl (1895m).
Those who are only here for the fat downhill can take a break here and prepare for the descent (there is a nice channel). Those who want to take the summit of Kreuzspitze, continue on the ridge with safe distance to the cornices. The summit can already be seen (not worthwhile for downhill). Anyway, if you want to go up you continue to the East (slightly right of the ridge) and climb the Ammergauer Kreuzspitze on steep cliffy terrain. The final is a not too demanding snowy edge to the exposed and view rich summit.
Along the ascent route. However you can enter the slope through a channel (approx. 45°) from Schwarzenköpfl).
Kompass Karte 05: Oberammergau / Ammertal, 1:35.000