Put the first 6 ingredients - dates, butter, sugar, water, cinnamon and bi carbonate of soda into a pot and bring up to the boil.
Simmer until the dates break up and the mixture turns into a very dark bubbly mass. Stirring occasionally.
Take off the heat and cool till just warm. Mix in the eggs flour and baking powder into the pot, and stir until well combined.
Pour into the prepared tin and into the pre-heated oven for 35 to 40 minutes. Test with a skewer into the centre . When it comes out clean the cake is done. Otherwise bake another 10 minutes
Frosting: Beat the soft cream cheese and butter till light and fluffy. Add the vanilla and 1 cup of sugar. beat till fluffy and well combined. Add the remaining sugar 1/2 a cup at a time and then the lemon. taste . You can add more lemon or a little more sugar if you would like.
Puréed dates: Put the dates into a pot with the water and simmer stirring occasionally until you have a nice soft sauce. Put into the fridge to chill.
Spread the date purée over the cake and sprinkle with cashews. Cut into even sized pieces.