B747 pilot reported temporary loss of aircraft control due to encountering Clear Air Turbulence during cruise.

Narrative

Deviating around weather between ZZZZ and ZZZZZ (north of Country X) at night.At the top of clouds and clear of weather but hit sudden moderate turbulence that gave an altitude deviation between 300-400'; stick shaker for 1-2 seconds. Then suddenly the turbulence returned to light turbulence.Notified ATC of the moderate turbulence.Cause: Clear Air TurbulenceSuggestions: Create a radar that detects Clear Air Turbulence