Preheat oven to 350°F (175°C). Grease and flour a 9x5 inch loaf pan.
In a medium bowl, whisk together flour, baking soda, and salt.
In a large bowl, cream together butter and sugar until light and fluffy. Beat in eggs one at a time, then stir in vanilla extract.
In a small bowl, mash bananas and sour cream together.
Gradually add the dry ingredients to the wet ingredients, alternating with the banana mixture, beginning and ending with the dry ingredients. Beat until just combined.
Pour batter into prepared pan and bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean.
Let cool in pan for 10 minutes before transferring to a wire rack to cool completely.
For the frosting, beat cream cheese and butter together until smooth. Gradually add powdered sugar, beating until light and fluffy. Stir in vanilla extract and milk.
Frost cooled cake and enjoy!
Notes
For extra flavor, add chopped walnuts or chocolate chips to the batter. Store in an airtight container at room temperature.