Quest giver: Zombie TK Baha
Location: Southwestern corner of Hallow's End
You get this trophy from completing the final of five quests he gives. All of them are collecting brains for him to eat. First quest you need 10, second you need 25, third is 50, fourth is 100, final is 250.
You acquire brains from zombies by killing them with a headshot. Brains only count towards quest completion if they are picked up AFTER the quest has started, so make sure you go turn it in and get the next part before you continue so you get credit.
There's plenty of zombies around so as long as you are concentrating on getting those headshots, you should complete this easily.
I used an assault rifle. Highly recommend assault rifle, SMG, or any gun that has a good fire rate with decent damage and accuracy. Avoid elemental weapons, since any damage that does the final tick of health that is NOT a headshot will not drop a brain.