01 - In a mixing bowl, combine milk, granulated sugar, cornstarch, salt, and eggs. Whisk thoroughly until the mixture is smooth and free of lumps.
02 - Transfer the pudding mixture to a heatproof bowl suitable for pot-in-pot cooking. Cover the bowl tightly with aluminum foil.
03 - Pour 1 cup water into the Instant Pot insert. Position a trivet inside, then place the covered bowl onto the trivet.
04 - Secure the Instant Pot lid. Cook using Manual or Pressure Cook setting for 10 minutes, followed by a 10-minute natural pressure release. Complete with a careful quick release if pressure remains.
05 - Remove the bowl from the Instant Pot. Whisk the pudding until silky. Blend in butter and vanilla extract until fully incorporated.
06 - Allow the cooked pudding to rest and cool for 10–15 minutes, stirring occasionally to prevent a skin from forming on the surface.
07 - In a trifle dish or individual cups, create alternating layers of vanilla wafers, sliced bananas, and warm pudding. Continue layering, ending with a pudding layer on top.
08 - Refrigerate the assembled pudding for at least 1 hour for optimal texture and flavor development.
09 - With an electric mixer, whip the heavy cream and powdered sugar in a clean bowl until soft peaks form. Pipe or spread the whipped cream over the chilled pudding.
10 - Just before serving, decorate with additional banana slices and vanilla wafers as desired.