Here's Suzy Wong's recipe and instructions:
A 7 or 8 inch square tin lined with greaseproof paper/baking parchment and the oven set to 180/GM4 moderate oven.
A small saucepan in to which you put
150g butter
150g chocolate, at least half of it should be plain
On a low heat and let it melt together and leave it to cool slightly
Then beat together in a bowl
2 eggs
1 tsp vanilla extract
175g caster sugar
Until creamy looking
Then sift in
100g plain flour
1 big tablespoon of drinking chocolate
And a quarter of a teaspoon of salt
Throw in 100g walnuts
And the chocolate and butter and mix well.
Scrape it into the lined tin and bake it for 20 minutes.
Then have a look at it, the top should be pale and cracking slightly, like a dried up muddy puddle, the body of the mix will still be slightly wobbly. If it isn?t like this then leave it in for another 3 minutes.
Leave to cool in the tin and then slice into portions
DO NOT take it in to the bathroom and scoff the lot