When leaving the runway 7R in EDDF, all of a sudden 2 engines out - though there was definitely enough fuel. I started the APU and restarted both engines, all looked good (except for some systems, most noteably the FMses reset bc of the loss of electricity). Any idea what that is? Not saying it is not fun - just wondering what that was! 2 engines out simultaneously is a pretty rare thing in reality I would guess.