Preheat the oven to 180c (160c fan). Line a 22cm springclip tin with baking paper.
Sift the flour, cocoa, salt and baking powder into a large bowl. Add the sugar, breaking up any lumps, and the eggs.
Start beating the mixture slowly to ensure that the mixture doesn't fly out, then a littl faster until the mixture is smooth. Scrape down the sides of the bowls and mix once more. Add the mixture to the tin and bake for 50-60 minutes.
Once baked, turn out the tin onto a cooling rack and leave to cool. Once cooled, cover with buttercream icing or ganache and enjoy. Best served after 24 hours.