Sharing a memoized val between different Speks

[ravenblackdusk]

I want to share a memoized val between different Speks, since the memoized val is an org.testcontainers DockerComposeContainer which takes several minutes to be evaluated. But none of the CachingModes seem to work. This leaves me with the option to write all tests in a single Spek. How can I share a memoized val between different Speks?