Preheat your oven to 350°F (175°C) and grease and flour two 8-inch round cake pans.

Whisk together the all-purpose flour, baking soda, salt, and ground cinnamon in a large mixing bowl.

Beat together the unsalted butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition, followed by vanilla extract, mashed bananas, and sour cream.

Gradually incorporate the dry mixture into the wet ingredients, stirring until just combined.

Divide the batter evenly between the prepared pans and bake for 28-32 minutes or until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes before transferring them to wire racks to cool completely.

Prepare the frosting by beating together cream cheese and unsalted butter until smooth, then gradually adding powdered sugar and heavy cream.

Once cooled, place one cake layer on a plate, spreading frosting on top, then add the second layer and frost the top and sides.

Garnish with extra toasted walnuts, chill before serving.