Pre-heat your oven to 180°C/160°C fan.Line two 20cm round sandwich tins with greaseproof paper or reusauble baking liners.
Place the raisins (150g) into a bowl and cover them with water.
Coarsely grate the carrot (225g).
Whisk together the oil (225ml sunflower or vegetable oil) and brown sugar (200g) until combined.
Whisk in the eggs (3 large) until combined. The mixture will lighten in colour and look glossy.
Sift in the self-raising flour (250g), bicarbonate of soda (¾ tsp), ground cinnamon (1½ tsp) and ground mixed spice (½ tsp). Fold them into the other ingredients.
Drain the raisins and add them and the grated carrot to the cake mixture. Fold them into the other ingredients.
Split the cake mixture between the two pre-prepared tins. Use the back of a spoon or a spatula to spread the mixture evenly in the tins.
Bake for 35-40 minutes until a skewer inserted into the cake comes out clean. Once baked, remove the cakes from the oven and leave them to cool in their tins for 10 minutes, before removing the tins and placing the cakes onto a wire rack to cool completely before decorating.