01 - Place softened cream cheese in a medium mixing bowl. Using a hand mixer on medium speed, beat until completely smooth and creamy, approximately 1-2 minutes.
02 - Add powdered erythritol and vanilla extract to the cream cheese. Continue mixing on medium speed until fully incorporated and no sweetener granules remain visible, about 1 minute.
03 - With mixer running, gradually pour in heavy whipping cream. Increase speed to high and continue beating until mixture becomes light, airy, and holds soft peaks, approximately 2-3 minutes. Fold in lemon zest if using.
04 - Divide cheesecake fluff evenly among four serving glasses or bowls. Top with fresh berries and chopped nuts if desired. Serve immediately for a mousse-like texture, or refrigerate up to 48 hours for a firmer consistency.