Step 1: In a large mixing bowl, whip the cold heavy cream with an electric mixer on high speed until stiff peaks form. Be careful not to overmix, as it can turn granular. Set the whipped cream aside.
Step 2: In a separate large bowl, using the same electric mixer (or a clean one), beat the softened cream cheese on medium speed until it is completely smooth and creamy, with no lumps.
Step 3: Add the sugar-free instant banana pudding mix to the cream cheese. If using, add the vanilla extract and sugar substitute. Beat on medium speed until all ingredients are well combined and the mixture is smooth.
Step 4: Gently fold the whipped cream into the cream cheese mixture using a spatula. Mix until just combined and no streaks of cream cheese or whipped cream remain. Do not overmix, as this will deflate the fluff.
Step 5: Transfer the banana pudding cheesecake fluff to a large serving dish, individual parfait glasses, or small bowls. Smooth the top with a spatula.
Step 6: Cover the dessert and refrigerate for at least 2 hours to allow it to set properly and for the flavors to meld beautifully. For best results, chill longer, up to 4 hours.
Step 7: Before serving, garnish with fresh banana slices and crushed sugar-free vanilla wafers, if desired. Enjoy your decadent, guilt-free treat!