Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a large bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
Mix in the mashed bananas, sour cream, and milk until combined.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Do not overmix.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool in the pan for 10 minutes. Then transfer to a wire rack to cool completely.
While the cake cools, prepare the cream cheese frosting. In a medium bowl, beat the softened cream cheese and butter together until smooth and creamy.
Add the powdered sugar gradually, beating until smooth and fluffy.
Mix in the vanilla extract until combined.
Once the cake is completely cool, spread the cream cheese frosting evenly over the top.
Slice and serve.