Preheat the oven to 170 °C. Grease the cake tin with the butter or baking spray and line the base and long sides with baking paper.
Finely mash the bananas. Beat the eggs and honey with the mixer in a mixing bowl until light and airy. Fold the almond flour and baking powder through the batter as lightly as possible. Fold in the blackberries. Spoon the batter into the cake tin.
Bake the banana bread for about 50 mins. until golden brown and cooked. To check if your cake is cooked, insert a clean (wooden) skewer into the centre of the cake and remove it. The cake is ready if the skewer comes out clean. Cool on a wire rack. Garnish with extra blackberries or other berries.