Preheat the oven to 180 C / Gas 4. Line the sides and base of a 23cm square baking tin with grease proof paper and also grease the tin with a light coating of butter. Finely grate the zest from the orange and squeeze out the juice. Pour the juice over the raisins in a bowl, stir in the zest then leave to soak.
Put the sugar into a mixing bowl with the oil and add the eggs. Mix lightly with a wooden spoon. Add the carrots, raisins with orange juice and zest, walnuts and ground almonds; stir to mix.
Mix the flours, bicarbonate of soda, baking powder and cinnamon then shift into the bowl of mixture. Lightly mix together. Pour the mixture into the prepared tin.
Bake for 40 to 45 minutes. Test with a skewer and if it comes out clean it is done. Leave it in the tin to cool for about 5 minutes and then take it out. Take the paper off and let it go cold on a wire rack.
Beat the icing sugar, soft cheese, lemon juice and orange zest in a small bowl until it resembles single cream. Spread over the cooled cake.
You can cut the cake into squares. I have found that if you put it in an airtight tin it will keep for 3 to 5 days uniced or in the fridge if iced.
I bake this cake in my microwave and it comes out great. I have the Sharp R-959M-A combination convection. I use the Auto Cook Cake feature and the cake takes about 25 minutes.
I have used a 23cm silicone cake tin for this cake (from TKmax). The advantage being you don't need to grease or use any lining paper.