- Make the pudding: Sift together flour and cornstarch, and set aside. In a large bowl, whisk eggs, yolks, and 4 ounces sugar until smooth and incorporated. Whisk in flour mixture until smooth. In a heavy-bottomed pot, combine milk, remaining 4 ounces sugar, butter, vanilla bean, and bananas, and bring to a boil. Remove from heat, cover with plastic wrap, and allow to steep for about 45 minutes. Remove plastic and discard vanilla pod, then puree mixture with an immersion blender until smooth. Return to stove over medium-high heat. After mixture reaches a simmer, remove from heat and begin streaming a small amount of liquid into egg mixture, whisking well as to not cook the eggs with the heat. Continue until most of the liquid is incorporated into eggs, then pour egg mixture back into pot and return to medium-high heat, whisking constantly, until mixture comes to a boil and thickens. Remove from heat, whisk in peanut butter, and season with salt and vanilla extract.
- Make the meringue: Preheat oven to 200 degrees. Puree banana and set aside. In the bowl of a mixer fitted with whisk attachment, whip whites until foamy, then stream in sugar, cornstarch, cream of tartar, and salt. Whip on high until whites are stiff and glossy. Remove from mixer and stir in pureed banana. Spread evenly on cookie sheets (or pipe evenly into desired shapes) and dehydrate in oven until crispy, about 1 to 1½ hours.
- To assemble: In a glass bowl, alternate layers of pudding with vanilla wafers. Top with peanut butter powder and shards (or shapes) of banana meringue.