I got it on 25/05/14 by selecting chapter select final level on uber difficulty, when you first gain control of your character, change to easiest and finish.
If they patch the above, currently chapter select the final and complete the entire chapter on uber difficulty works.
If they patch that or its too hard then starting a new game on 999 bonus mode works and having unlimited ammo and respawning after death with 999 health makes it easier than the normal game on the easiest setting and unlocks the trophy (its also fun with double weapons and laying down unlimited fire)
If you need help on how to defeat a boss I think I used the below walkthrough I just used the PS4 search engine which does the job beautifully.
http://www.primagames.com/games/wolfenstein-new-order/covera...