Preheat oven to 350 degrees F. Use pan spray on 9x5 inch pan then coat with cinnamon sugar. Set aside until needed.
Mash bananas. Set aside until needed.
Using a hand mixer, cream together butter and sugar until light and fluffy (1-2 minutes). Add eggs and vanilla.
In a separate bowl, combine flour, baking soda, and salt.
Add mash banana and flour mixture to sugar mixture. Mix until just combine. Don't over mix.
Pour half the banana bread batter in bottom of coated pan and smooth. Sprinkle 1/4 cup cinnamon sugar on top then pour and smooth remaining batter on top. Sprinkle with remaining cinnamon sugar.
Bake for 60-70 minutes until a toothpick poked in the center comes out clean.