Bake bananas at 355°F for 10 minutes or until blackened. Set aside to cool down completely.
After cooling down, peel and mash bananas until smooth.
In a large bowl, combine salt, honey, olive oil, eggs, vanilla, mashed bananas, and baking soda. Mix until well combined.
Pour whole wheat flour into the mixture, about ½ cup at a time. Whisk until fully combined.
Whisk walnuts and half of the blueberries into the batter mixture.
Pour the batter into a loaf pan. Sprinkle the remaining blueberries on the top of the batter. Place the pan in the preheated oven.
Bake at 355°F for 40 minutes on the lowest rack. For the last 25 minutes, cover the pan with aluminum foil to avoid the top overbrowning.
Remove the loaf from the oven and allow it to cool completely. Transfer the loaf to a plate, slice and serve.