Preheat the oven to 180C/Gas Mark 4.

Rub some oil around the inside of three 20cm/8” round cake tins or insert a baking liner.

Measure the cocoa and flour into a bowl, stir to combine then sieve into another mixing bowl.

Add the caster sugar, and stir with a whisk to combine.

Break the eggs into a large jug, add the milk, oil and vanilla extract and beat together well. Pour the egg mixture into the mixing bowl and mix everything together with the whisk. Add the boiling water and beat well.

Divide the runny mixture between the tins. Bake for 35–40 minutes.

Cool the cakes for a couple of minutes in their tins then turn them out onto a wire rack.

Break the chocolate into squares.

Put the cream and sugar into a saucepan and stir over a medium heat until about to boil. Remove the pan from the heat, add the chocolate and stir until combined.

Allow to cool, stirring regularly until a thick paste starts to form which may take 8–10 minutes.

Divide the mixture between the top of the three cold sponges and spread it out over each. Immediately place the sponges one on top of the other and leave to set.