Preheat oven to 350°F (175°C) and line a 9x13-inch pan with parchment paper.
In a large bowl, mix mashed bananas, sugar, melted butter, eggs, and vanilla extract.
In another bowl, whisk flour, baking soda, and salt.
Combine dry ingredients with wet mixture until just blended.
Pour batter into the prepared pan and spread evenly.
Bake for 25–30 minutes or until a toothpick comes out clean.
Let cool completely before frosting.
To make frosting, beat cream cheese and butter until smooth. Add powdered sugar and vanilla, and mix until creamy.
Spread frosting evenly over cooled bars. These Banana Bars with Cream Cheese Frosting are ready to slice and serve.