Place banana in single layer on a baking tray or container. Cover and freeze until frozen.

Partially thaw frozen banana and mixed berries, then place in a blender. Process the fruit until well combined.

Add almond milk and process until smooth and of a sorbet-like texture, occasionally scraping down the sides of processor. This can take 3–4 minutes.

Spoon the ‘nice cream‘ into a 4–cup airtight container or a loaf tin. Cover and freeze. Sprinkle the ice cream with pistachio nuts and serve.