Line a small bread tin or lunch box with greaseproof paper.
After steaming the peeled sweet potato for around 15 minutes or until soft, allow it to cool.
Add the dairy-free milk, cooled sweet potato, almond butter, maple syrup and vanilla extract to a blender and blend until smooth.
Either in the microwave or over a double-boiler melt the vegan chocolate.
With the blender running, stream in the melted chocolate and blend until well combined and smooth.
Pour the mixture in to the prepared bread tin, level and sprinkle with hemp seeds or any topping of your choice. Cover with foil and pop it in the freezer to set for at least an hour. When set, remove from the freezer and cut in to slices to serve.
Store in the freezer or for a softer mousse slice, the fridge.