01 -
Preheat oven to 350°F (175°C). Thoroughly grease two 8-inch (20 cm) round cake pans. In a medium bowl, whisk together flour, baking soda, and salt until well combined.
02 -
In a large mixing bowl, beat butter and sugar until light and creamy, about 3 minutes. Add eggs one at a time, incorporating each fully. Mix in vanilla extract. Fold in mashed bananas and sour cream until just combined.
03 -
Gradually add the dry ingredients to the wet mixture, mixing on low speed until just incorporated. Gently fold in chopped walnuts and white chocolate chips, being careful not to overmix.
04 -
Divide batter evenly between the prepared pans, smoothing the tops with a spatula. Bake for 30-35 minutes or until a toothpick inserted in the center comes out clean and edges begin to pull away from sides.
05 -
Allow cakes to cool completely on wire racks. Place one layer on a serving plate and spread with half the custard. Top with second layer and remaining custard. Arrange banana slices and walnuts decoratively on top.