Preheat oven to 350°F (175°C) and grease a cake pan.
In a bowl, whisk together flour, baking soda, and salt.
Beat butter and sugar with a stand mixer until creamy.
Add eggs and vanilla, then mix in mashed bananas.
Alternately add flour mixture and buttermilk.
Pour batter into pan and bake for 35-40 minutes.
Cool and serve plain or with cream cheese frosting and banana slices