Takes practice to avoid the over "over the top caramelly, malt and melanoiden laden beer" (huckdavidson above) and throw in the extra diacetyl from the malt. Difficult to get the flav just right with decoction.
What really helped mine was after 50F primary (FG < 25% OG), do a diacetyl rest for several days, at house temp (72F). Same container, no transfer.
That cleared out the butter bigtime.
Then transfer to serving keg.