In a medium saucepan, whisk together the granulated sugar, cornstarch, and salt until well combined.
Gradually add the whole milk to the dry mixture while whisking constantly. Next, whisk in the two large egg yolks until fully incorporated.
Place the saucepan over medium heat, stirring constantly until the mixture thickens and begins to bubble, about 7-10 minutes. Remove from heat and stir in the vanilla extract.
Transfer the custard to a bowl, cover it with plastic wrap, and refrigerate until cooled, about 1-2 hours.
While the custard cools, whip the heavy cream in a mixing bowl until stiff peaks form.
Once the custard is chilled, gently fold in the whipped cream using a rubber spatula.
Slice the bananas and dip them lightly in lemon juice to prevent browning.
In your baking dish or trifle bowl, layer vanilla wafers, sliced bananas, and custard mixture until ingredients are used up, finishing with custard on top.
Cover the assembled pudding with plastic wrap and refrigerate for at least 4 hours or overnight.
When ready to serve, top with additional whipped cream and crushed vanilla wafers. Enjoy!