Preheat oven to 180°C fan. Grease and line a 900g loaf tin.

Toast the walnuts first: spread on a baking tray and roast at 180°C for 8–10 minutes until fragrant and slightly darkened. Let cool before chopping roughly. This step is non-negotiable — raw walnuts are fine, toasted walnuts are transformative.

Mash the bananas thoroughly in a large bowl.

Add butter, sugar, eggs, and vanilla. Stir to combine.

Sift in flour, baking soda, salt, cinnamon, and nutmeg. Fold gently until just combined.

Fold in the toasted walnuts and blueberries.

Pour into the prepared tin and bake for 60–70 minutes. Test with a skewer.

Cool in the tin for 15 minutes before turning out. Try to wait — it slices much cleaner when cool.