$ set var=Foo

$ set var
var=Foo

$ set var=Bar & perl -MWin32 -e "print Win32::ExpandEnvironmentStrings('%var%')"
Foo

$ set var
var=Bar

$ set var=Baz & perl -MWin32 -e "print Win32::ExpandEnvironmentStrings('!var!')"
Baz

$ set var
var=Baz