Step 1: In a large mixing bowl, combine the cold milk and both packets of sugar-free instant banana pudding mix. Whisk vigorously for about 2 minutes until the mixture thickens. Let it sit for 5 minutes to set completely.
Step 2: In a separate large bowl, beat the softened cream cheese with a hand mixer or stand mixer until light and fluffy, about 2-3 minutes.
Step 3: Gently fold the prepared banana pudding into the beaten cream cheese until just combined.
Step 4: In a clean, chilled bowl, whip the cold heavy whipping cream and powdered erythritol on high speed until stiff peaks form, about 3-5 minutes.
Step 5: Carefully fold the whipped cream into the banana pudding and cream cheese mixture until no streaks remain and the mixture is uniformly light and fluffy.
Step 6: Arrange a single layer of sugar-free vanilla wafers (or crushed graham crackers) at the bottom of a large trifle dish, 9x13 inch baking dish, or individual parfait glasses.
Step 7: Top the wafer layer with a generous amount of fresh banana slices.
Step 8: Spoon about half of the banana pudding cheesecake fluff mixture over the bananas, spreading it evenly.
Step 9: Repeat the layers: wafers, banana slices, and the remaining banana pudding cheesecake fluff.
Step 10: Garnish the top with crumbled wafers, extra banana slices, or a dollop of whipped cream if desired.
Step 11: Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow flavors to meld and wafers to soften.
Step 12: Serve chilled and enjoy your Decadent No Bake Sugar Free Banana Pudding Cheesecake Fluff!