Method

1. Heat cream and soy milk in a small, heavy-based saucepan over medium heat until simmering. This should take about 5 mins. You can tell it is at a simmer when small bubbles start to appear around the edges. Do not let it boil. Stir in the cinnamon and vanilla. Take it off the heat.
2. Whisk together the egg yolks and caster sugar in a large mixing bowl, using a wire whisk or hand blender, until thick and pale. Pour the soy milk mixture into the egg mixture and quickly whisk until well combined.
3. Place the banana and one cup of the mixture into a blender and process until smooth. Pour into the remaining mixture and stir until well combined.
4. Clean the saucepan and return to medium heat. Pour in the mixture and cook, stirring constantly, until thickened to form a custard. This will take about 3 minutes. You can check if it is thick enough by dipping the spoon into the custard and then running your finger along the back of the spoon. If the fingermark remains in place, it is ready.
5. Cool in the saucepan until there is no steam rising from the custard, then transfer to a heatproof container. Cover the surface of the custard with plastic wrap to prevent a skin forming and chill in the fridge for at least 4 hours or until completely cold. Blitz the walnuts in a food processor until they resemble coarse breadcrumbs. Set aside.
6. Pour the cold custard into the bowl of an ice cream maker, set to desired setting and churn. When machine specifies you can add 'mix-ins', sprinkle in the walnuts and resume churning. Once mixture is frozen transfer to a freezer-safe container and freeze for up to one week.

Notes: I used the Breville Smart Scoop ice cream maker to create this recipe. I pre-cooled the machine for 15 minutes before churning and set it to the first setting in the ice cream section.