Pre-heat the oven to 170℃(fan) or 180℃ electric. Grease the sides and base of a loose-bottomed 22cm cake tin and line with non-stick baking paper (as there's no oil in this recipe you need extra non-stick support).
Add the lemon juice to the soya milk and leave it to curdle for a few minutes.
Mix the flour, baking powder, cinnamon, and salt together in a large bowl and mix well. Stir in the chopped walnuts (if using) and the raisins.
Add the carrot, maple syrup, vanilla essence and apple sauce to the curdled soya milk. Whisk well to combine.
Pour the wet ingredients into the dry and briskly mix making sure you include the flour at the bottom of the bowl. Don't worry if it’s a bit lumpy - it's more important not to knock all the air out the mix.
Pour the mix into the prepared cake tin and use a spatula to scrape the bowl.
Jiggle the bowl to make sure the mix has spread out then tap it on the worktop. Place in the oven and bake for 20-25 minutes, turning halfway through. Check the cake is cooked using a skewer or toothpick.
Once cooked, remove from the oven. Leave the cake to rest in the tin for 5 minutes then carefully tip out upside down onto a cooling rack. Gently peel off the non-stick baking paper and turn over. Leave the cake on the rack to cool completely.
To make the topping, drain the soaked cashew nuts and put them in a small high-speed blender pot. Add the soya milk, maple syrup and lemon juice and blend until smooth. Add a little extra soya milk or lemon juice if the mix is too thick for your blender.
Spread the frosting evenly over the top of the cake. Scatter the chopped walnuts over the top and gently sprinkle the ground cinnamon over the top (I use a small sieve).
Keep in an air-tight container in the fridge for up to 4 days.
