Preheat the oven to 180°C (356°F) and grease or line the 20 cm loaf pan.

Melt the butter in a saucepan over medium heat until golden brown and nutty-smelling.

Strain the browned butter and let the 75 g cool until cold or barely warm.

Whisk the 2 eggs with the white sugar and brown sugar until thoroughly combined.

Whisk in the cooled 75 g brown butter and 50 ml sunflower oil.

Fold the 400 g ripe banana puree into the wet mixture until smooth.

Combine the flour, baking powder, salt, and mixed spices in the second bowl.

Fold the dry ingredients into the banana mixture just until no dry flour remains.

Pour the batter into the prepared loaf pan and scatter the dark chocolate over the top.

Bake for approximately 45 minutes, until a tester inserted in the center comes out clean or with a few moist crumbs.

Cool the banana bread in the pan before slicing and serving.