Preheat oven to 180 degrees Celsius (350 degrees Fahrenheit).
Drain away most of the water from soaking the dates, leaving behind about 5 tablespoons.
Use a food processor or blender to whizz the dates into a smooth purée.
Place the puréed dates in a bowl with all the other ingredients and mix well.
Transfer into a greased baking dish - I used a 7inch/18cm round springform baking tin.
Bake in oven for around 20 minutes - it doesn't matter if it's still a little gooey when you take it out of the oven as it will firm up when cooled.
Keeps covered in the fridge for up to a few days.
Video
Notes
*Several readers have told me they made this cake oil-free by replacing the oil with applesauce, which seems to have worked well. So please do this if you're looking for an oil-free cake!