Brooklyn Blackout Cake – Clandestine Cake Club – Americana – 18.08.12

A few weeks ago it was my second Clandestine Cake Club event, and the theme was Americana. I knew pretty quickly that I wanted to attempt the Hummingbird Bakery’s Brooklyn Blackout Cake as I’d had my eye on this bad boy in all it’s chocolatey glory for a while! I had intended to try a trial run, but unfortunately I just didn’t find the time in the run up to the event, so the night before I took to the kitchen and hoped for the best! I was planning on doing the sponges the night before and then doing the chocolate custard the following morning and assembling it, however in the end I decided to do the custard the night before as well and let it cool over night, I would really recommend that if you try this recipe you do the same. The custard needs a long time to cool and thicken and so it’s not really something you can do in a rush. As you’ll see from the pics below the consistency of the custard changes once it’s cooled properly so had I left it until the day I wanted to assemble it, I would have had a bit of a nightmare. Once assembled the cake needs 2 hours chilling in the fridge, so ensure you leave yourself plenty of time before you’re planning on serving it!


  • 100g unsalted butter at room temperature
  • 260g caster sugar
  • 2 eggs
  • 1/4 teaspoon vanilla extract
  • 45g cocoa powder
  • 3/4 teaspoon baking powder
  • 3/4 teaspoon bicarbonate of soda
  • a pinch of salt
  • 170g plain flour
  • 160ml whole milk

For the Chocolate Custard:

  • 500g caster sugar
  • 1 tablespoon golden syrup
  • 125g cocoa powder
  • 200g cornflour
  • 85g unsalted butter, cubed
  • 1/2 teaspoon vanilla extract

Three 20cm cake tins, base-lined with greaseproof paper


  1. Preheat the oven to 170 degrees C (325 Degrees F) Gas 3.
  2. Put the butter and sugar in a freestanding electric mixer with a paddle attachment (or  use a handheld electric whisk) and cream until light and fluffy. Add the eggs one at a time, mixing well and scraping any unmixed ingredients from the side of the bowl with a rubber spatula after each addition. Turn the mixer down to slow speed and beat in the vanilla extract, cocoa powder, baking powder, bicarbonate of soda and salt until well mixed. Add half the flour, then all the milk, and finish with the remaining flour. Mix well until everything is well combined.

3. Pour the mixture into the prepared cake tins and smooth over with a palette knife.

4. Bake in the preheated oven for 25-30 minutes. Leave the cakes to cook slightly in the tins before turning out onto a wire cooling rack to cool completely.

5. For the Chocolate Custard: Put the sugar, golden syrup, cocoa powder and 600ml water into a large saucepan and bring to the boil over a medium heat, whisking occasionally. I would recommend you use a BIG saucepan for this as later on the mixture does grow considerably and I found myself having a frantic rush tipping it into a big pot to avoid it spilling over the edge of a smaller pan I’d started with!

6. Mix the cornflour with 120-200ml water, whisking briskly as you add the water. The mixture should be the consistency of thick glue so add more water if it’s too thick (do not exceed 250ml). Whisk gradually into the cocoa mixture in the pan over a medium (not high) heat. Bring back to the boil, whisking constantly. Cook, whisking constantly for a few minutes until quite thick. Remove from the heat and stir in the butter and vanilla extract. Pour into a bowl, cover with cling film and chill until very firm.

 This was what the hot custard looked like. It’s very shiny and slick and dark. After it’s cooled it’s much thicker and has a texture more like margarine, which is much easier for spreading:

7. Slice a thin layer off one cake and put in a food processor. Process into fine crumbs. Put one cake on a cake stand and spread one-quarter of the custard over it. Place a second cake on top and spread another quarter of the custard over it. Top with the last cake and spread the remaining custard over the top and sides

8. Cover with the crumbs and chill for 2 hours

I took the cake out of the fridge for about an hour before I served it which allowed it to return to room temperature a bit. It was without a doubt one of the richest chocolate cakes I have ever tasted. I found that there was a lot of leftover chocolate custard so I actually made 2 layers of vanilla sponge the following day when I had some family over for lunch and used it to fill and top that, which was a great combination and wasn’t quite as rich.

Another great use for the custard would be to heat it up and pour over ice-cream! Delicious!!

2 thoughts on “Brooklyn Blackout Cake – Clandestine Cake Club – Americana – 18.08.12

  1. Americana is such an awesome theme for cake club!! I may suggest this to my organiser :D

    I love pudding in cakes but have avoided making it myself as it takes so much time, but yours looks delicious Jen :] x

  2. Thanks Claire! It was a really rich mixture, a must for chocolate lovers! :)
    There were some great cakes for the Americana theme, I’d definitely recommend it as it gives so many different routes to go down for cake ideas! :) x

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