Making the Cake:

1. Preheat the Oven: Preheat to 350°F (175°C). Grease and flour a 9×13-inch pan (or line with parchment paper).
2. Mix Dry Ingredients: In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
3. Cream Butter and Sugars: In a large bowl, use a hand or stand mixer to beat the butter, granulated sugar, and brown sugar until light and fluffy (about 2-3 minutes).
4. Incorporate Wet Ingredients: Add eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
5. Add Bananas and Sour Cream: Mix in the mashed bananas and sour cream until fully incorporated.
6. Combine Dry and Wet Mixtures: Gradually add the dry ingredients to the wet mixture, folding gently until just combined. Do not overmix.
7. Bake: Pour the batter into the prepared pan. Smooth the top with a spatula. Bake for 45-50 minutes or until a toothpick inserted in the center comes out clean.
8. Cool: Allow the cake to cool completely in the pan on a wire rack before frosting.

Making the Cream Cheese Frosting:

1. Beat Cream Cheese and Butter: In a large bowl, beat the cream cheese and butter together until smooth and creamy (about 2-3 minutes).
2. Add Sugar and Flavoring: Gradually add the powdered sugar, vanilla extract, and salt. Beat on low speed initially to avoid splattering, then increase to high speed until fully combined and smooth.
3. Adjust Consistency: If the frosting is too thick, add 1-2 teaspoons of milk. If too thin, add more powdered sugar.

Frost and Decorate:

1. Frost the Cake: Spread the frosting evenly over the cooled cake using an offset spatula or butter knife.
2. Optional Decorations: Garnish with banana slices, chopped nuts, or a dusting of cinnamon for an extra touch.