Preheat oven to 350℉. Grease and flour two 9-inch round deep cake pans. Set to the side.

To make the cake, in a large bowl, combine the flour, baking powder, and salt. Set aside. In a separate large mixing bowl, cream together the butter and sugar on high for about 5 minutes or until light and fluffy. Add the eggs and egg yolks, one at a time, mixing well after each addition. Stir in the vanilla extract and scrape the bottom and sides of the bowl with a rubber spatula to ensure everything gets evenly combined. Add the dry ingredients and the buttermilk to the batter, alternating between the two. Begin and end with the dry ingredients. So add a bit of dry, mix until just combined, buttermilk, mix, dry, mix, milk, mix, and dry, until it's all incorporated. Divide the batter between the prepared cake pans. Give them a few raps on the counter to dislodge any air bubbles.

Bake for about 25 to 30 minutes or until golden brown and a toothpick inserted in the middle comes out clean. Remove from oven and allow to cool for about 10 minutes. Run a knife along the edge of the cake and then invert to remove the cake from the pan. Allow to cool completely on a wire rack.

To make the pudding, in a medium saucepan, whisk together the flour, sugar and salt. Slowly whisk in the milk until evenly combined. Stir in the egg yolks and place over medium-high heat. Cook, stirring often, until the mixture bubbles and has thickened, about 5 to 8 minutes. Remove from heat and stir in the butter and vanilla extract. Pour into a bowl, through a fine mesh sieve to remove any lumps. Cover the surface directly with plastic wrap and chill for at least 1 hour or over night.

To make the whipped cream, beat the heavy cream on high with the powdered sugar and vanilla extract until soft peaks form, about 8 to 10 minutes.

To assemble the cake, trim the tops of the cooled cakes to even them out, and then cut them each in half so you end up with four thin layers. Place on layer on a cake stand or plate. Then pipe out a border of whipped cream along the edge. Pour a third of the vanilla pudding into the center and spread out into an even layer. Top with sliced bananas and crushed cookies. Top with a cake layer and repeat twice more. Once the last cake layer as been place, cover the cake roughly with whipped cream. Allow to chill in the fridge for about 30 minutes to set. Cover the cake with more whipped cream, only this time, make sure to really coat it and smooth it as best you can. Decorate the top and sides with whipped cream, wafer cookies, crumbs and banana slices. Let rest in the fridge for about 1 hour before slicing and serving! Enjoy!