Preheat your oven to 170C. Grease (I used oil) and line the bottom of a 23cm springform cake tin.
Melt your broken up chocolate gently, either over a bowl of simmering water, or in a microwave (I have never dared to do it this way before now, but it worked fine, just watch it constantly, stir every 20 seconds, and take it out before it's totally melted - about 3-5 minutes on medium will do it). Set it to one side.
Mix your cocoa with boiling water and vanilla extract. Set aside.
Combine flour and salt with bicarb in a separate bowl. Again, set aside!
Now beat eggs, sugar and oil with an electric whisk for 3 minutes in yet another bowl. With a hand whisk it'll take longer, around 5 minutes, or until it becomes a little lighter and fluffier.
Finally, tip in your cocoa solution into the egg and oil mixture. Beat. Now tip flour in gradually into this mixture and beat again. Lastly, the melted chocolate and 20 or so cherries. Fold gently till all is combined.
Tip the lovely dark batter into your prepared tin and bake for 40 - 45 minutes. Test with a skewer (it should come out clean). Mine took about 43 minutes.
Let it cool for 15 minutes in the tin, then remove and place on a wire rack to cool.
Serve with creme fraiche and more cherries.