Heat the oven to 180C/160C fan/gas 4. Butter a 900g loaf tin and line the base and sides with baking parchment. Tip 100g of the chopped dark chocolate into a heatproof bowl along with the butter, and melt over a pan of simmering water, ensuring the base of the bowl doesn’t touch the water. Or, do this in the microwave in 20-second bursts. Set aside to cool slightly.

Beat the sugar and eggs together in a separate bowl using an electric whisk, until light and frothy. Sift in the flour, cocoa powder and a pinch of salt, and fold to combine. Fold in the melted chocolate mixture, then the bananas and remaining chocolate chunks.

Scrape the mixture into the prepared tin and bake for 50 mins until puffed up and a skewer inserted into the middle comes out clean. Leave to cool in the tin for 10 mins, then remove to a wire rack and cool completely. If you like, clean out the tin and tip the loaf back into it for easier transport. Will keep in an airtight container for up to four days.