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. Ensure no lumps remain.
02 - Add powdered erythritol and vanilla extract to the cream cheese. Continue beating on medium speed until fully incorporated and mixture appears glossy, about 30 seconds. Fold in lemon zest if using.
03 - With mixer running, gradually drizzle in heavy whipping cream. Increase speed to high and whip until mixture thickens significantly and holds soft peaks when beaters are lifted, 2-3 minutes total. Texture should resemble mousse.
04 - Divide mixture evenly among four serving glasses or bowls. Top with fresh berries and chopped nuts if desired. Serve immediately for lightest texture, or refrigerate up to 48 hours for firmer consistency.