Preheat your oven to 350°F (175°C). Grease and dust your cake pan with butter and flour.

In a medium-sized bowl, whisk together all-purpose flour, baking powder, baking soda, salt, and optional cinnamon.

In a large mixing bowl, cream together unsalted butter, granulated sugar, and brown sugar using an electric mixer for 2-3 minutes until fluffy.

Beat in eggs one at a time, then add vanilla extract, mashed ripe bananas, and sour cream until smooth.

Gently fold dry ingredients into wet ingredients until just combined.

Pour batter into prepared pan and bake for 30-35 minutes until a toothpick comes out clean.

For the frosting, melt unsalted butter in a saucepan, add brown sugar and heavy cream, stir until bubbling, then whisk in powdered sugar and vanilla until smooth.

Once the cake is completely cool, frost with caramel frosting.