Preheat the oven to 350 degrees and grease a loaf pan. Grease with butter, spray oil, etc, and dust with flour.
In a large bowl beat together the sugar, egg and vanilla until combined.
Add the butter and beat until smooth.
Beat in the buttermilk and bananas.
In a separate bowl, mix together the flour, salt, baking soda, baking powder and cinnamon.
Slowly stir the dry ingredients into the wet until it's fully incorporated.
Pour the batter into your prepared loaf pan.
Make your crumble by mixing together all of the ingredients in a small bowl.
Using your fingers crumble across the top of your batter evenly.
Bake for 45-60 minutes or until a tooth pick comes out clean.
Allow to cool completely before removing from the pan and slicing.
