Preheat the oven to 190°C/170°C (fan) and prepare a 20cm square, deep tin and line it with non stick baking paper

In a bowl, cream together the butter and sugar. Once creamed whisk the eggs into the mixture

Next sieve the flour and cocoa powder into the egg mixture

Then, in a food processor, whizz the chocolate until finely chopped

Transfer the mixture to the prepared tin and bake for 30 minutes. After 30 minutes insert a skewer into the centre to make sure it is cooked. If it comes out clean it is cooked, if it comes out with mixture put it back into the oven and check every 5 minutes to see if it is cooked

Once cooked leave it to cool and then, once cooled cut it into 16 pieces and enjoy