Preheat the oven to 350℉ (325℉ if using glass) and grease the bottom and corners, or line with parchment, an 8 x 4 inch loaf pan.
Mix topping ingredients together, set aside.
Mash bananas in a bowl. Stir in buttermilk, set aside.
Combine flour, baking soda, baking powder, salt and cinnamon in a medium bowl, set aside.
Cream together the softened butter, brown sugar and vanilla until combined, about 2minutes.
Add eggs, one at a time, and beat until smooth and creamy.
Add ⅓ of the dry mixture to the creamed mixture and mix until combined. Add ½ of the mashed bananas and mix until combined. Repeat until all of the banana and flour mixtures have been added.
Fold dried blueberries into the mixture until evenly distributed.
Pour the batter into your prepared loaf pan, sprinkle topping on and bake for 60 minutes, or until a toothpick inserted into the center comes out clean.
Let cool in the pan for at least 10 minutes before removing to a cooling rack.