Double Chocolate Oatmeal Stout Recipe

A beautiful recipe to make with a massive grain bill producing a smooth, dark wort which looks fantastic! I tasted it before fermentation because I just couldn’t wait and there’s lots of different flavours going on in there, bring on the end product! Just to let you all know I made this beer using the Grainfather therefore the quantity of mash and sparge water used will be different to other all grain methods.  The amount of sparge water used is low because the Grainfather recirculates the wort through the mash when sparging which achieves an efficient yield of wort from the grain.

A quick update, this beer has now been in the bottle for just over 6 weeks and it tastes amazing, nice and smooth with a chocolatey after taste that lingers on the tongue! Perfect!

Makes approx 23 litres Pre boil amount approx 30 litres


Quantities for the Grainfather:

Mash water approx 21.00 litres

Sparge water approx 9.00 litres

Working out water quantities for other set ups:

If using a different all grain set up the general rule for the mash water is a ratio of 2.5:1 water/litres to grain/kilograms.  So here’s the maths:

Grain bill 6.7kg x 2.5 litres = 16.75 (mash water)

1kg of grain holds 1.1 litres water

Grain bill 6.7 x 1.1 = 7.37 litres of water saturated in the grain, this will never sparge out.

16.75 (mash water) – 7.37 = 9.38 amount of wort extracted if you didn’t sparge.

Pre boil amount 30 litres – 9.38 = 20.32 This is the amount of sparge water needed to reach a pre boil amount of 30 litres which should work out at a post boil amount of approximately 20 litres. Some people prefer to do a full volume mash at 30 litres to avoid sparging, often done using the brew in a bag method.

Approx ABV 6.94% – It can be watered down in the fermenting vessel to lower the ABV if required.

Start gravity approx: 1.070

Final gravity approx: 1.018

The Mash:

Mash at 70 degrees C for 90 minutes.  Mashing at this higher temperature produces a beer with more body due to the lower conversion of starch to fermentable sugars. Make sure that when mixing your grain into the water you get rid of any dough balls.


Heat your sparge water to 80 degrees C and ensure that you extract as much of the wort as possible.

The Boil:

Boil for 60 minutes in total.  Add 28 grams of Goldings and 14 grams of Northern Brewer hops at the start of the boil just after it’s calmed down into a nice rolling boil. At 45 minutes add 1 tablespoon of Irish Moss and then at 50 minutes add the remaining hops. Once the boil is complete cool as fast as possible to a fermentable temperature.  I used the Grainfather which has a counter flow cooling system which is extremely efficient, cooling the wort from 90 degrees C to 24 degrees C within minutes!

Fermentation and Bottling:

Ferment for 7 days at around 20-24 degrees C. Once finished you can transfer to another fermenter to take it away from the sediment bed and allow it to clear again, however this isn’t necessary I’ll bottle mine straight from the primary vessel into the bottles, with one carbonation drop per bottle as I don’t want it to be too fizzy. The Fermentis yeast S-04 compacts the sediment at the bottom to a jelly so the beer was lovely and clear even before bottling.  Once bottled I’ll leave it in a dark cool place for at least one month to carbonate and condition.  I’ll probably try one bottle and if it needs longer to mature I’ll give it another month.

Happy Brewing!

Take a look at our YouTube video showing the brew in a bag method:

Check out our Mosaic Pale Ale Recipe!

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