EEA Family permit for BC dependent in EU - possibility to travel?

Hi all,
this is my situation currently:
British citizen currently living and working in the EU. Applied for and was granted a EU residence card for my dependent spouse. Now we are planning to return to the UK under the Surinder Singh route. So recently in Oct we made an application for EEA family permit, which is currently still in processing. We submitted my dependent spouse's passport for this application.
My question is: as Christmas is approaching, and we always spend time with family and friends in the UK for this (and also having booked tickets and so on) I would like to travel back to the UK this Christmas with my spouse (EEA family permit Surinder Singh route application currently pending with HO). But can my spouse just travel with EU residence card and no passport? Or alternatively, should we request for a passport return - whilst the application is on-going so we can make this trip to the UK and return back to the EU?

Thanks in advance!

My question is: as Christmas is approaching, and we always spend time with family and friends in the UK for this (and also having booked tickets and so on) I would like to travel back to the UK this Christmas with my spouse (EEA family permit Surinder Singh route application currently pending with HO). But can my spouse just travel with EU residence card and no passport?

No, she needs her passport. EU residence card is not an EU citizen ID card and cannot be used separately for travelling.

Or alternatively, should we request for a passport return - whilst the application is on-going so we can make this trip to the UK and return back to the EU?

Not sure re SS route, but with standard EEA FP you can either initially keep your passport (ie choose this service when you do biometrics) or you will end up with application withdrawn.

See also Entering the UK as the holder of an Article 10 or 20 residence card.