In a medium saucepan, whisk together the milk, heavy cream, sugar, cornstarch, and salt over medium heat. Continue whisking until the mixture thickens and begins to bubble, about 5-7 minutes.
Remove the saucepan from heat and stir in the vanilla extract. Let the pudding cool for about 10 minutes.
In a 9x13-inch dish, layer half of the vanilla wafers on the bottom. Top with half of the sliced bananas. Pour half of the pudding over the bananas and wafers.
Repeat the layers with the remaining vanilla wafers, bananas, and pudding.
Spread the whipped cream evenly over the top layer of pudding.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, preferably overnight, to allow the flavors to meld and the pudding to set.
Serve chilled and enjoy!