Bartlett's Bitter Brew

Bartlett's Bitter Brew is the November brew from the Brew of the Month.

Source
This is only available to members of the Brew of the Month Club, which can only be joined during Brewfest.

All members of the Club get free sample of the brew in their in-game mail at start of November. Should you want more, your local Brew of the Month Club Brew Vendor sells it in stacks of six till the end of November.

On the first of November, members receive the following in game mail: