Preheat oven to 160°C (140°C fan-forced). Lightly grease a deep 23cm round cake tin and line with baking paper, making sure the paper extends 10cm above the top of the tin.
Combine the flours, cocoa and bicarbonate of soda together in a large mixing bowl, stirring until well combined.
Place espresso shot into a jug and top up with boiling water to 180ml. Pour coffee into a large saucepan over a very low heat, add butter, sugar and chocolate, stirring to combine. Continue stirring until chocolate and butter have melted and mixture is smooth. Set aside to cool slightly. Add the eggs, oil and milk to the chocolate mixture, whisking until well combined.
Create a well in the centre of the flour mixture and pour the chocolate mixture into the centre, stirring until well combined. Pour the mixture into the prepared cake tin. Place tin on a baking tray and bake in preheated oven for 2 hours or until a skewer comes out of the centre cleanly. Remove from oven, place on a wire rack and allow cake to cool completely in tin.
To make ganache, place prepared chocolate in a medium mixing bowl. Place cream in a small saucepan over a medium heat, bring to just below boiling point. Pour over chocolate and gently stir to combine. Leave to stand for several minutes before stirring again. Repeat process until chocolate has melted, making sure mixture is not stirred too much.
Allow ganache to cool until it is a spreadable consistency. Remove cake from tin and place on a serving plate. Using a spatula, ice the cake, starting with the sides and finishing with the top. Allow ganache to set before serving.