Blackout cake

100g unsalted butter, at room temperature

260g caster sugar

2 eggs

1/4 tsp vanilla extract

45g cocoa powder

3/4 tsp baking powder

3/4 tsp bicarbonate of soda

a pinch of salt

170g plain flour

160ml milk

Chocolate custard

500g caster sugar

1 tbsp golden syrup

125g cocoa powder

200g cornflour

85g unsalted butter, cubed

1/2 tsp vanilla extract

three 20cm cake tins base lined with greaseproof paper

Preheat the oven to 170°c.

Put the butter and sugar in a bowl and beat together until light and fluffy. Add the eggs one at a time, mixing well and scraping any unmixed ingredients from the side of the bowl. Slowly beat in the vanilla extract, cocoa powder, bicarb, baking powder and salt until well mixed. Add half the flour, then all the milk, and finish with the rest of the flour, mix well until everything's combined. Pour the mixture into the cake tins, and smooth over. Bake for 20-25 minutes. Leave to cool slightly in the tins and then turn out onto a wire rack.

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. Mix the cornflour with 120-200ml water, whisking as you add the water if its too thick add more water but no more than 250ml. Gradually whisk into the cocoa mixture in the pan over medium heat. Bring back to the boil, whisking constantly 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.

Sandwich and cover the cakes in the chocolate custard.