Make sure that the bowl of your ice cream maker has been in the freezer for long enough, mine takes 11 hours to fully freeze. Ideally you should make the ice cream base the day before you want to churn the ice cream.
You need to soak the cashews so that they are soft enough to blend to a smooth cream. Either cover them with plenty of boiling water and leave to soak for an hour, or cover with cold water and leave to soak overnight.
Place the porridge oats in a saucepan with half of the soy milk and bring to a gentle simmer, cook for about 10 minutes, stirring often to prevent the bottom from catching, until the oats are soft.
Drain the soaked cashews well then place them in a blender with the other half of the milk and blitz until smooth.
Add the cooked oat mixture to the blender along with the pumpkin puree, maple syrup, sugar, spices, oil and salt and blend until the mixture is very smooth. Pour into a bowl, cover and refrigerate until completely cold.
Once the ice cream mixture is thoroughly chilled, give it a good whisk then pour it into your ice cream maker and churn until it reaches soft serve consistency.
Once the ice cream is done churning, transfer it to a freezer-proof container and freeze for about 4 hours, until firm, before serving.