300g • 10 1/2 oz chocolate - good dark chocolate 70% cocoa solids (if you load dark choc use at least 50% cocoa solids)
300g • 10 1/2 oz • 2 1/2 sticks of butter (if using unsalted add 1/2 teaspoon of sea salt)
375g • 13 oz • 1 1/4 cups of packed light muscovado (brown) sugar
(if using 50% chocolate solids cut down to 325g / 11 1/2 oz / )
5 eggs medium to large
15 ml • 1 tablespoon of vanilla extract (not vanilla essence)
200g • 7 oz • 1 1/2 cups plain all purpose flour
Pre-heat the oven to fan 160C / 180C / 356 F / gas 4
9 inch (23 cm) square tin or 13 x 10 inch tin (34cm x 25 cm), lined with baking paper
Melt the chocolate and butter together in a bowl over pan of simmering water until melted, let steam escape now and again.
In a large bowl mix the eggs with the sugar and vanilla and whisk with an electric whisk for 1 minute until mixture well amalgamated.
Add firstly one tablespoon of chocolate to the egg mixture and whisk in well, followed by a second tablespoon, after this you can pour the remainder of the chocolate in, if you don't brings eggs and chocolate to same temperate to start with your mixture may seize up.
Add the flour and whisk in for few seconds or fold it in until the mixture is well combined. Pour into the prepare tin and bake.
For the 9 inch square tin bake between 30-40 mins. For the 13 x 10 inch ( 34cm x 25cm) bake between 20-25 mins.