Step 1: In a large bowl, whisk together the sugar-free instant banana pudding mix and cold unsweetened almond milk for about 2 minutes, until thickened. Place in the refrigerator to chill for at least 15 minutes.
Step 2: In a separate large bowl, beat the softened cream cheese with the powdered erythritol and vanilla extract until smooth and creamy, about 2-3 minutes. Make sure there are no lumps.
Step 3: Gently fold the chilled banana pudding mixture into the cream cheese mixture until just combined. Be careful not to overmix.
Step 4: In a clean, cold bowl, beat the cold heavy whipping cream with an electric mixer on high speed until stiff peaks form.
Step 5: Carefully fold the whipped cream into the banana-cream cheese mixture until light and fluffy. Do this in two additions to maintain the airiness.
Step 6: Gently fold in the sliced bananas. Reserve a few slices for garnish if you wish.
Step 7: Spoon the banana pudding cheesecake fluff into individual serving dishes or a large trifle bowl. Cover and refrigerate for at least 4 hours, or preferably overnight, for best results and to allow the flavors to fully meld. Garnish with additional banana slices just before serving, if desired.