Break the bananas into large pieces and freeze them overnight.
If you want to garnish the ice cream with the roasted hazelnuts, roast them for 15 minutes at 180°C, then roughly chop and keep aside in an airtight container (you can also do this the next day, of course).
The next day, add the frozen banana pieces to your food processor (I used my Ninja) and leave them to thaw for 5 minutes. Then add the almond butter, almond milk and cacao powder and blend, scraping down once or twice, until smooth and creamy. Serve immediately.
