Preheat the oven to 200°C and toast the walnuts on a baking sheet for five to six minutes until lightly browned. Cool, then roughly chop.
Reduce the oven temperature to 180°C and grease a 450g loaf tin with a little rapeseed oil and line with baking parchment.
Sift together the flours with the spices and raising agents in a bowl.
Weigh the bananas. You need 165g, and mash well. Place the mashed bananas in a bowl and blend with the salt, oil, maple syrup, vinegar and vanilla with a balloon whisk. Tip in the dry ingredients and fold through with a spatula until just blended, then fold in the walnuts.
Scrape the mixture into the loaf tin, leaving it a little domed in the middle. Slice the extra half piece of banana lengthways and place this on top to decorate. Sprinkle with a little demerara sugar all over the top and bake for 45 minutes, or until the top is browned and springs back when pressed. An inserted cocktail stick should come out clean.
Let the cake cool in the tin until just warm, then turn out onto a wire rack to cool completely. Brush the bananas with a little extra maple syrup to add a little shine.
Recipe from Nourish Cakes by Marianne Stewart, photography by Catherine Frawley (Quadrille, £15)
DISCLAIMER: We endeavour to always credit the correct original source of every image we use. If you think a credit may be incorrect, please contact us at info@sheerluxe.com.