Cream the butter and sugar together until light and creamy.

Melt the chocolate and add it to the creamed mix

Mix the egg into the creamed mix

Add the plain flour and cocoa powder and mix together to form a dough.

Bake at 160c for 10 minutes.

Melt the butter and chocolate together

Sieve the icing sugar into the chocolate mix. Stir together well to form a smooth paste.

Pipe 10g of filling onto a biscuit and sandwich together with another.

Store in a sealed container at room temperature and enjoy within a week.