We had an exercise recently involving LOTBE due Volcanic ash at FL160...
VERY interesting, and a potential booby trap as in the QRH for volcanic ash, there is no mention of "if thrust is lost on both engines"... You must combine both checklists.
You have to be quick, get out of the cloud, increase speed to light up engines, but at the same time start thinking about emergency landing fields/areas/ditching as you are at 10.000' without any working engine...
APU should not be started before exiting the ash cloud by the way, another thing omitted in the QRH.
CRM and checklist knowledge is crucial, combined with correct prioritization.
Not a test item but very valueable as training.