Preheat oven to 325 degrees
Cream together 1/2 cup of butter, 1 1/2 cups of sugar, and eggs
Add baking soda, salt, and 1 teaspoon of vanilla extract, mix well
Mash bananas in a seperate bowl until no large lumps are visible
Add bananas to batter and mix well

Add flour 1/2 cup at a time, stirring well after each addition
Line a jelly roll pan or rimmed baking sheet with parchment paper trimmed to fit, oil with a teaspoon of vegetable oil
Pour batter into prepared pan and spread evenly, bake 20-30 minutes or until lightly browned and cake springs back when tested

Immediately invert cake onto a clean kitchen towel dusted with confectioners sugar, remove parchment paper
Starting at the short end, carefully roll cake up into towel, cool completely on a wire rack
In a small bowl, combine 4 tablespoons of room temperature butter, cream cheese, and 1/2 teaspoon of vanilla extract, mixing until smooth
Stir in 1 cup of sifted confectioners sugar until smooth
Carefully unroll cooled cake and frost with cream cheese frosting to the very edges

Re-roll cake around filling and refrigerate at least 1 hour before slicing with a serrated knife
Dust with additional confectioners sugar before slicing
Store uneaten cake in the refrigerator, wrapped in plastic wrap