Decadent Birthday Cake - Chocolate & Peanut Butter Layer Cake

Rich chocolate sponge, layered with peanut butter cream, slathered in chocolate mousse frosting.

Chocolate and Peanut-Butter Birthday Layer Cake

A birthday request from my boy. He’s had a tough year, going through a postgraduate course without ever seeing his classmates or lecturers in person. He’s been gracious and good humoured throughout, fairly helpful in the house (when asked) and knows he’s luckier than so many others who’ve been locked up in student residences for weeks. As a treat, I asked him to name his desire for a birthday cake and he challenged me to make a dark chocolate and peanut-butter layered cake.

This is what I came up with. He’s great at pinging inspirational ideas for food off me, although they generally involve nuclear amounts of chilli. This one is a change from that trend, you’ll be glad to know. The salty crunch of the peanut butter makes the perfect contrast to the deep chocolately velvety cake. You do make quite a mess eating it unless it’s straight out of the fridge. We enjoyed it very much and I hope you do too. The picture doesn’t do it justice, really, so please use your imagination.

Serves 8 (small slices as it’s very rich)       Timings:  90 minutes, then time to chill.

For the cake:

• 3 eggs
  
• 100g caster sugar
  
• 100g plain flour
  
• 20g dark cocoa powder
  
• 20g butter
  
• 1 tablespoon sour cream

 
For the filling:

• 100g salted butter
  
• 100g crunchy peanut butter
  
• 200g icing sugar

 
For the topping:

• 100g salted butter
  
• 200g icing sugar
  
• 100g dark chocolate

 
Pre heat your oven to 180°C. Grease and line an 18cm cake tin – I like a loose bottomed one as it makes it much easier to get out.

Beat the eggs and caster sugar together energetically until fluffy. Melt the butter and let it cool slightly. Sieve the flour and cocoa powder together. Add the flour/cocoa to the beaten egg/sugar mixture one spoon at a time with the mixer going slowly and then pour the butter over the top and mix it in with a metal spoon.  Mix in the sour cream. Scoop the batter into your cake tin and bake 25-30 minutes until brown on top and a skewer comes out clean.  Cool the cake on a wire rack and remove from the tin, taking the paper off the bottom too. The sponge is quite moist due to the cream, so don’t worry if it looks less spongy than some cakes.

When cool, carefully cut the cake into three layers.

For the filling, whisk the butter and peanut butter together vigorously and add the icing sugar a spoonful at a time, covering your mixer with a tea towel to stop the sugar dust going all Christmassy on you. Sandwich the layers of cake together generously.

Make the topping:  melt the chocolate over hot water. Beat the butter and icing sugar together carefully, as above with a tea towel over the mixer, then stream in the melted chocolate and keep whisking. This makes quite a fluffy mousse-like soft buttercream icing.

Decorate the sides and top of the cake with the chocolate buttercream.

Keep the cake in the fridge to set the icing. It keeps for several days in the fridge but you need to keep it cool right up till serving.