I have now seen something twice, and I'm wondering if anybody can tell me
how to do it (e.g. a recipe):

A friend bought a chocolate cake from a world-champion (literally, he
claims) pastry chef, which was basically ganache, the whole cake. The cake
had a chocolate glaze, all around (top and sides) -- like, say, a Sacher
Torte. Except that this was a very, very thin glaze, and certainly not
hardened at all.

Then I saw this kind of thin glaze again on another occasion.

I make a chocolate cake with a ganache layer on top, and it occurred to me
that that this kind of thin, not-hardened glaze would be a nice thing to do
for it. But the only glaze recipes I know about give you a rather thicker
glaze, whereas this one seems to be millimeter thin, almost liquid -- and
yet somehow manages to be "set" at the same time.

Can somebody shed some light on this?

John