Preheat the oven to 350°F
Coat a 9x13-inch baking dish with non-stick baking spray. Set aside.
In a large bowl of a standing mixer, on medium speed, add the butter and brown sugar and mix until creamy.
Reduce the speed low speed, and add the vanilla and mix until combined.
Begin to add the eggs one at a time, continue to mix on low until well combined.
In a medium sized bowl add the flour and salt and whisk to combine.
Add the flour mixture to the butter mixture, slowly, mix until well combined.
Remove the bowl from the stand mixer and fold in the bananas.
Pour the batter into an even layer on the baking pan.
Bake for 45 minutes, or until the center is set.