1. Preheat the oven to 160°C fan/180°C. Grease two 20-centimeter cake tins with oil, then line with baking paper.
2. Weigh all the dry cake mix ingredients into a large bowl and stir together with a whisk to fully combine. (If the sugar is lumpy, you will have to sift it.)
3. Weigh all the wet cake mix ingredients, except the water and coffee, into a large bowl and whisk together. Make the coffee in a cup with the measured boiling water and instant coffee, pour it into the wet ingredients bowl and stir well.
4. Add the dry mix to the wet mix and stir well with a whisk to combine.
5. Divide the mixture evenly between the prepared tins (if you want to be precise, you can weigh the total batter, then divide it exactly in half). Bake for 35 minutes, or until a skewer inserted comes out clean.
6. Remove from the oven and allow to cool in the tin for 20 minutes before flipping onto a wire rack (allow to cool fully before adding the ganache you’re about to make).
7. To make the ganache, put the chocolate and the salt in a large heatproof bowl. In a saucepan, heat the cream with the malt extract until steaming but not boiling. Pour the hot cream over the chocolate and leave for 1 minute. Use a whisk to stir the ganache from the middle outwards – so as not to whisk in any air – until silky and beautiful. Let the ganache sit for 10 minutes.
9. Take a large plate with a lip. Place a cooled cake on the plate and spoon over enough ganache to cover the top. Don’t worry if it spills over the edges, we kind of want this. Place the next cake on top. Pour the remaining ganache all over the top, without a care in the world. Use a spoon to guide it over, making sure plenty of ganache is falling down the sides. Put the cake in the fridge for 20–30 minutes.
10. Remove the cake from the fridge and, using a small offset palette knife, scoop up the set ganache from the edges of the plate and spread over the sides to create a smooth finish. It really is that easy and effortless.