In a medium saucepan, whisk together the granulated sugar, all-purpose flour, and salt. Set aside.

In a separate medium bowl, whisk the egg yolks until light in color. Gradually whisk in the whole milk until well combined.

Pour the milk and egg yolk mixture into the saucepan with the dry ingredients. Whisk continuously over medium heat. Bring to a gentle boil, then reduce heat to low and continue to cook, whisking constantly, for 2-3 minutes until the mixture thickens significantly. It should be thick enough to coat the back of a spoon.

Remove from heat and stir in 1 teaspoon of vanilla extract. Pour the pudding into a clean bowl, press plastic wrap directly onto the surface to prevent a skin from forming, and refrigerate for at least 2 hours, or until completely chilled.

In a large mixing bowl, using an electric mixer, beat the cold heavy cream, confectioners' sugar, and 1 teaspoon of vanilla extract on medium-high speed until stiff peaks form. Be careful not to overbeat.

Once the custard pudding is completely chilled, gently fold about two-thirds of the whipped cream into the pudding using a rubber spatula. This will lighten the pudding and give it that signature Magnolia Bakery texture. Keep the remaining whipped cream for topping.

To assemble, in a large serving bowl or trifle dish (approximately 3-4 quart capacity), arrange a single layer of Nilla wafers at the bottom.

Top the wafers with a layer of sliced bananas. Spread about one-third of the pudding mixture evenly over the bananas.

Repeat the layers: wafers, bananas, pudding, until all ingredients are used, finishing with a layer of pudding.

Cover the dish with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the wafers to soften and the flavors to meld. Before serving, you can dollop the reserved whipped cream on top, if desired.