Preheat your oven to 160°C (325°F). Line 3 x 18 centimetre or 2 x 20 centimetre cake tins with baking paper.
Soak the pitted dates with the bicarbonate of soda and hot coffee in a bowl for approximately 20 minutes.
Blend the soaked dates and liquid in a food processor until fairly smooth.
Add the Muscovado sugar, butter, maple syrup, cinnamon, mixed spice, vanilla extract, and eggs. Process until well incorporated.
Add the self-raising flour. Mix briefly until just combined. Scrape down the bowl and blades.
Divide the batter evenly between the prepared tins. For accuracy, weigh the total batter and divide by the number of tins.
Bake for 40 to 45 minutes until the cakes have risen, feel springy to the touch, and a knife inserted into the centre comes out clean.
Cool in the tins for 10 minutes. Then transfer to a cooling rack to cool completely.