Preparation

• Preheat the oven to 350°F with a rack in the center position. Grease and flour two 8-inch cake pans.
• Heat a large skillet over medium-high heat. Add ¼ cup of the butter, 2 tablespoons of the brown sugar, and 2 cups of the bananas and cook until the bananas are caramelized, 5 to 7 minutes. Transfer the bananas to a medium bowl and mash with a fork.
• In a large bowl, whisk together the flour, baking powder, baking soda, and salt.
• In a stand mixer fitted with a paddle attachment, beat the remaining ¾ cup of butter on high speed until smooth and creamy, about 1 minute. Add the sugar and the remaining ½ cup of brown sugar and beat on high for about 2 minutes, or until creamed together. Add the eggs and the vanilla and beat until combined. Add the mashed caramelized bananas and beat until combined.
• With the mixer on low speed, alternate adding ⅓ of the flour mixture and ⅓ of the buttermilk, being careful not to over mix. Stir in ¾ cup of the walnuts, if using.
• Pour the batter into the prepared cake pans, dividing evenly. Bake for 40 to 45 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow the cakes to cool completely in the pans set on a wire rack.
• Make the whipped cream. Using a handheld or stand mixer fitted with a whisk attachment, beat the cream, sugar, and vanilla on high speed until stiff peaks form.
• Using a large serrated knife, slice off the tops of the cakes to create a flat surface. Carefully slice each cake in half (horizontally), creating 4 separate (equally thick) layers. Place 1 cake layer on your cake stand, or serving plate.
• Add about ⅕ of the whipped cream to the top of the cake and spread into an even layer. Top with an even layer of the remaining banana slices. Top with the second cake layer, cut side down. Repeat with remaining whipped cream, banana slices and cake layers. Spread the remaining whipped cream over the top and sides of the cake in an even layer. Decorate with remaining walnuts and white chocolate.