Directions:

Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans.
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a large mixing bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla extract.
Mix in the sour cream and mashed bananas until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the chopped walnuts and white chocolate chips.
Divide the batter evenly between the prepared cake pans.
Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack to cool completely.
Once the cakes have cooled, spread half of the creamy custard over the top of one layer. Place the second layer on top and spread the remaining custard over the top.
Garnish with banana slices and whole or halved walnuts. Serve immediately or refrigerate until ready to serve.