Blackout cake

I make to no claim to this being the original or authentic Brooklyn Blackout cake. My only claim is that it is a winner, and I adapted it from a British recipe which claimed it was a Brooklyn blackout cake. I have adapted it for the Thermomix.

Brooklyn blackout cake

  • Servings: 10-12
  • Difficulty: medium
  • Print



140g unsalted butter

100g vegetable oil

150g buttermilk

100g coffee ( I used nespresso)

2 large eggs

1 tsp vanilla extract (I used the seeds of a vanilla pod)

250 g light soft brown sugar

250g plain flour

50g cocoa powder

2 tsp baking powder

Pinch of salt

1 tsp baking soda ( bicarbonate of soda)

Filling and covering

250g golden caster sugar

500g full cream milk

50g cornflour

2 tsp espresso powder ( I used a shot of nespresso)

2 tsp vanilla extract ( I used seeds of a vanilla pod) For even more flavour you can pop the scraped pod into the TM bowl and remove before using.

140g chocolate chips, min 70% cocoa

Preheat oven 180°C/360°F

Prepare tin by spraying and lining base. I used 3 x6″/15cm because I wanted a tall cake but this works in 2x20cm/8″


Custard filling (make first as it has to cool for several hours.)

This is a piece of cake for Thermomix owners- perfect custard or crème pâtissière every time while you do something else.

Pop all the ingredients ( excluding the chocolate chips) into the TM bowl.

Cook for 7 minutes/ 80°/sp4

Add chocolate chips/callets (remove pod if using) blend 20 seconds/sp8 to melt chocolate

Cover, Set aside and chill


'Whisk' the dry ingredients – flour, baking powder, baking soda and cocoa powder, salt, light brown sugar- by turbo pulsing sp 3 a couple of times, tip out and reserve

Melt butter in TM bowl 50°/sp2

Add oil, buttermilk, Coffee, and eggs and mix well sp 4

Add the dry ingredients and mix thoroughly sp3/4

Divide mixture evenly between prepared pans and bake in preheated oven.

Larger 8″ cake pans wil take 25-39 minutes, 6″ pans 20-25 minutes. Always check your cakes at least 5 minutes before the due time. Remove when a skewer comes out clean.

Refrigerate cakes before levelling and filling with chocolate custard.

I found the custard to be delicious BUT it is a lot more slippery than a traditional buttercream. The custard has to be completely cold and the cake has to be level otherwise it will rapidly be a leaning tower of Pisa. If you are making an 8″ cake this will make it easier.

I didn't cover the cake but there is enough custard to do that or serve on the side or just use in another desert.

While this version of the blackout cake doesn't have black stout as an ingredient it is very rich and yummy.

Since there seem to be many versions I'm sure I'll try another in the near future and report back 🙂

2 Comments Add yours

  1. Amy says:

    Died for …. 🙂

    Liked by 1 person

  2. nowathome says:

    It looks so yummy!!


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