butterscotch milk stout

You can try to promote the growth of the compound diacetyl, which will give a buttery, butterscotch-like flavor to your beer. From the article linked below, here are some ways to promote diacetyl:

-Proper yeast strain selection
-Underpitching yeast
-Do not aerate your wort
-Begin fermentation at the high end of the yeast tolerance
-Reduce fermentation temps to low end of the yeast tolerance during “exponential growth”
-Cold crash as soon as terminal gravity is met, let the yeast floc out, then bottle immediately

http://www.whitelabs.com/beer/Diacetyl_Time_Line.pdf

With all that said, there may be an easier way…

 

Just use Ringwood yeast.

 

Yeast probably hate you.

 

I'm sorry. This idea sort of repels me. I had to deal with some unwanted diacetyl this summer and I won't soon welcome it back. Someone also recently gave me some cookies with butterscotch chips -- only politeness and control of my gag reflex prevented me from tossing my cookies.

RE: Ringwood Yeast. The only time I used it, I had a wonderful brown ale. No infamous buttery badness.

 

I had it work perfectly with a diacetyl rest, proper pitching and oxygenation, but minus the d-rest I had some issues.