Having done a few double engine failure on final scenarios in the sim,I think the reality is you are doing well if you get out a Mayday call and Brace Brace to the cabin.
Don't stall the aeroplane and keep energy for a flare.
I'm surprised at the Boeing recommendation to keep leave the flap alone too although I know that's the case.
If you are flying at Vref +5 the speed drops below Vref before the failure is even recognised in most cases. (B737-800 F30)
Better lucky than good and so much the better if you are both!