For the Brown Sugar Pastry Cream: Set a fine mesh strainer over a 13- x 9-inch baking pan; set aside. In a small saucepan, heat milk over medium heat, stirring occasionally, until steaming, about 3 minutes. Meanwhile, in a medium bowl, whisk together egg yolks, egg, brown sugar, flour, cornstarch, and salt. Whisking constantly, gradually add warm milk to egg mixture in bowl until well combined. Pour egg mixture into saucepan.

Cook over medium-low heat, whisking constantly, until mixture thickens and begins to bubble, about 4 to 5 minutes. Continue to cook, whisking constantly, for 1 minute. Remove from heat and gradually stir in butter and vanilla until butter is melted and mixture is well combined.

Immediately pour mixture through prepared fine-mesh strainer and press gently; discard any solids. Press a piece of plastic wrap or buttered parchment paper directly onto surface of pastry cream, chill in refrigerator until cold, about 1 hour.

For the Caramelized Bananas: While pastry cream cools, in a large skillet, combine brown sugar, butter, cinnamon, and salt, and cook over medium heat, whisking frequently, until butter is melted and mixture is bubbly, about 3 minutes.

Carefully add bananas, spreading them into as even a layer as possible. Cook, stirring occasionally, until bananas are softened, 3 to 4 minutes. Transfer banana mixture to a large bowl, stir in vanilla until combined. Chill in refrigerator, uncovered and stirring occasionally, until cooled, about 1 hour.

For the Whipped Cream: In a stand mixer fitted with a whisk attachment, whisk cream, sugar, and vanilla on medium-high speed until medium-stiff peaks form, 2 to 4 minutes. Alternatively, whip cream by hand . Using a flexible rubber spatula, fold 1 cup of whipped cream into chilled pastry cream until just combined.

To Assemble Trifle: In the bottom of a 4-quart trifle bowl, arrange half of banana bread cubes, packing tightly and crumbling as needed. Layer half of the pastry cream over banana bread, followed by half of the caramelized bananas, then half of the cookies. Top with half of the remaining whipped cream.

Repeat layers once more, finishing with whipped cream. Garnish with pecans, if using. Serve.