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

 Prepare Dry Ingredients:
In a medium bowl, whisk together the all-purpose flour , baking soda , and salt . Set aside.

 Cream Butter and Sugar:
In a large mixing bowl, cream together the softened butter  and granulated sugar  until light and fluffy. Beat in the eggs  one at a time, then stir in the vanilla extract .

 Add Wet Ingredients:
Mix in the sour cream  and mashed bananas  until well combined.

 Combine Wet and Dry Ingredients:
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the chopped walnuts  and white chocolate chips .

 Bake the Cakes:
Divide the batter evenly between the prepared cake pans. Bake 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.

 Assemble the Cake:
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 and Serve:
Garnish with banana slices  and whole or halved walnuts.
Enjoy