Allow the cream cheese and butter to soften at room temperature for about 15–20 minutes so they blend smoothly.
Add the softened cream cheese and butter to a mixing bowl. Using a hand mixer or stand mixer, beat for 1–2 minutes until completely smooth and creamy.
Add the powdered erythritol, heavy cream, vanilla extract, and a pinch of salt to the bowl. Mix on low speed at first, then increase to medium-high and beat for 2–3 minutes until the mixture becomes thick, fluffy, and light.
Stop the mixer and scrape down the sides of the bowl with a spatula to ensure everything is evenly mixed. Beat again briefly if needed.
Transfer the finished fluff into an airtight container, smoothing the top with a spatula.
Refrigerate for at least 1 hour to allow the fluff to firm up and develop its thick, mousse-like texture.
Scoop into small portions and serve chilled. Enjoy as a snack, dessert, or keto-friendly sweet treat anytime.