Line a 20 x 20cm square tin with parchment. Roughly chop the dates and cover with 100ml boiling water. Leave to soak for 10 mins.

Put the banana in a bowl, mash with a fork, then stir in the cinnamon, vanilla, a pinch of sea salt and the soaked dates along with their liquid.

Tip the mixture into a food processor with half of the walnuts and 100g of the oats. Pulse until you have a thick paste. Tip into a bowl and combine with most of the remaining nuts, oats and hemp seeds.

Heat the oven to 180C/160C fan/gas 4. Press the mixture into the lined tin, top with the remaining nuts and seeds and, bake for 20-25 mins until golden and firm. Leave to cool completely before cutting into nine squares.