Preheat your oven to 150°C fan.
Line and grease an 8-inch round cake tin.
Melt the milk chocolate in short burst s in the microwave until smooth. Go slowly and at a low temperature. You could also use a double-boiler.
Add the eggs and sugar to a bowl with an electric whisk. Whisk the eggs and sugars until light and foamy. This will take a few minutes so it’s worth using an electric whisk but of course you can use good old fashioned elbow grease.
Once light and foamy, you can slowly add the melted chocolate. Keep whisking to incorporate and then add the oil.
Now add flour, cocoa, bicarbonate of soda and salt. Add the water and the coffee. Mix well to combine and then pour into your prepared tin.
Bake for 1 hour to 1 hour and 15 minutes. The cake is ready if the skewer comes out clean. If there are any crumbs attached to the skewer, pop the cake back into the oven for several minutes.
Once cooked, remove the cake from the oven and leave to cool completely in the tin.