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