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Brooklyn blackout cake

Brooklyn blackout cake

This very dark chocolate cake was created at a bakery in Brooklyn, New York, during the Second World War, the name derived from the blackouts the city experienced at the time – this is Martha Collison's version

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  • Serves12
  • CourseCake
  • Prepare45 mins
  • Cook30 mins
  • Total time1 hr 15 mins
  • Pluscooling

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  • 250g plain flour
  • 325g light brown soft sugar
  • 75g cocoa powder
  • 2 tsp bicarbonate of soda
  • 125g butter
  • 284ml tub Essential Buttermilk
  • 150ml milk
  • 2 British Blacktail Free Range Medium Eggs

For the chocolate custard filling

  • 350ml whole milk
  • 300g caster sugar
  • 1 tbsp golden syrup
  • 50g cocoa powder
  • 50g cornflour
  • 50g butter, cubed
  • 1 tsp vanilla extract


  1. Preheat the oven to 160°C, gas mark 3 and grease and line 3 x 20cm round, loosebottomed sandwich tins. Put the plain flour, brown sugar, cocoa powder and bicarbonate of soda into a large bowl, then whisk to combine. Melt the butter in a small saucepan.

  2. Whisk the buttermilk and milk into the melted butter, then beat in the eggs.

  3. Pour the wet mixture into the dry ingredients and whisk until a smooth batter forms. Evenly scrape the cake mixture into the prepared tins and smooth the tops with a spatula.

  4. Bake for 25-30 minutes, swapping the cakes around for the last 10 minutes, until risen and a skewer inserted into each centre comes out clean. Allow to cool completely before coating

  5. While the cakes cool, make the chocolate custard filling. Combine the milk, caster sugar, golden syrup and cocoa powder in a large saucepan, and warm over a medium heat, stirring occasionally, until the mixture boils.

  6. In a separate bowl, combine the cornflour with 75ml cold water and whisk until smooth. When no lumps remain, slowly pour the cornflour mixture into the saucepan, whisking continuously. Whisk over the heat for 2-3 minutes, until it thickens considerably. Allow to boil for 1 minute, then remove from the heat and stir in the butter and vanilla extract. Pour the mixture onto a parchmentlined baking tray, cover with another sheet of parchment to stop a skin forming, and leave to chill completely

  7. When ready to assemble the cake, use a serrated knife to trim the tops of the cakes so each one is completely level. Place the offcuts into a mini food processor and blitz to crumbs, or crumble between your fingers in a bowl.

  8. Place the bottom layer of sponge onto a cake stand and spread with chocolate custard. Repeat with the remaining 2 layers, then cover the cake completely with custard using a palette knife. Chill for at least 1 hour to solidify. Coat the outside of the cake with the crumbs, then chill until ready to serve. The cake will keep for 2-3 days in the fridge.


Typical values per serving when made using specific products in recipe


2,092kJ/ 498kcals



Saturated Fat












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