Heat oven to 350 degrees.
Grease a 9x5 pan and set aside.
Beat your butter and sugar together in a large bowl until light and creamy.
Add in your eggs one at a time till blended.
Mix in your bananas and vanilla.
Mixing slowly, add in your flour, baking powder, baking soda and salt until just combined.
Pour half of your banana bread mixture into your prepared pan.
Mix your cinnamon and sugar in a small bowl.
Sprinkle half of your cinnamon sugar over your batter.
Spread your remaining batter in the pan. Sprinkle the remaining cinnamon sugar over the top.
Bake for about 50 minutes until a toothpick comes out clean.
Cool on a cooling rack for about 5 minutes, before careful removing bread from pan to cool completely!