To Make the Banana Pudding: Combine bananas, eggs, milk, cornstarch, sweetener, salt, and vanilla in a blender. Blend until smooth. Pour into a medium saucepan. Cook on medium heat until thick, whisking constantly.
(Note: It is important that you stir constantly, or lumps will form.) Once filling becomes thick, (like a pudding consistency), remove from heat, and let cool. Refrigerate for at least 30-60 minutes. Once banana pudding has chilled, fold in 1 cup Tru Whip.
To Make the Trifle: Start with a enough wafers or graham crackers to fill the bottom of your container (s), then cover the cookies with some of your sliced bananas then the pudding, then a layer of whipped topping. Repeat these layers and top with whipped topping and some crushed cookies if desired! Store in fridge until ready to serve.
Note: This recipe makes 1 large trifle, or 4-8 individual trifles, depending on size of glass used.