Serves 6 to 8
2 and 1/4 cups milk
1 vanilla bean, split lengthwise, seeds scraped and reserved
4 large eggs, separated
3/4 cup sugar
1/4 cup cornstarch, sifted
1/2 teaspoon kosher salt
3 tablespoons unsalted butter
2 tablespoons dark rum
8 ounces vanilla wafers (about 2/3 of a 12oz box)
3 ripe bananas, sliced into 1/4-inch rounds
1/2 teaspoon cream of tartar
Lightly grease a 2-quart baking dish.
Combine 2 cups of the milk with the vanilla bean and reserved seeds in a heavy-bottomed saucepan, place over medium heat, and bring to a low boil. Remove from the heat and discard the vanilla bean.
Whisk together the egg yolks and 1/2 cup of the sugar in a large bowl. Combine the remaining 1/4 cup milk with the cornstarch and 1/4 teaspoon of the salt in a small separate bowl and stir to dissolve the cornstarch. Stir the cornstarch mixture into the egg mixture.
Stir a small amount of the heated milk into the yolk mixture to temper the eggs. Whisk the yolk mixture back into the saucepan with the milk mixture, place over medium-low heat, and cook, stirring constantly, for about 5 to 7 minutes, until the mixture thickens. Remove from the heat, transfer to a bowl, and add the butter and rum, stirring until the butter melts.
Preheat the oven to 350 degrees Fahrenheit.
Cover the bottom of the prepared dish with one-third of the wafers. Arrange half the banana slices in a layer over the wafers and cover with half the pudding. Place another third of the wafers on top of the pudding, followed by the remaining bananas and the remaining pudding. Arrange the remaining wafers in a ring around the edges of the dish, inserting them halfway into the pudding.
Place the egg whites, cream of tartar, and remaining 1/4 teaspoon salt in a glass or metal bowl and beat with an electric mixer on medium speed until light and frothy. Increase the speed to high and beat to soft peaks. Slowly add the remaining 1/4 cup sugar, beating constantly, until the whites are shiny and hold stiff peaks, about 3 minutes. Do not beat the whites past this point or they will separate and become grainy.
Spread or pipe the meringue on top of the pudding with a spatula or pastry bag and tip, making sure to cover the pudding completely to prevent the meringue from shrinking when baked. Form peaks by repeatedly drawing a knife or spatula across the meringue and then in an upward motion, or by piping with a pastry bag and ending with an upward motion.
Bake for 8 to 10 minutes, until the tips of the meringue are golden brown. Remove from the oven and let cool for 10 minutes before serving.