Line a loaf tin with foil or cling film

Melt the butter and chocolate in a bowl in the microwave, or over a very low heat in a pan on the hob.

Beat the eggs, chocolate flavor icing sugar and vanilla extract until light and fluffy. Add the melted butter and chocolate to the egg mixture.

Spread the layer of chocolate mix at the bottom of the tin. Add the layer of biscuits on top of the chocolate mix. Then alternate chocolate mix and biscuits until the mix runs out. The final layer should be chocolate mix.

Refrigerate the cake for at least an hour.

Cut the cake into slices with a sharp knife.