Chill the tools: Place your mixing bowl and beaters in the fridge for 10 minutes. Cold tools help the cream whip faster.
Whip the cream: In the chilled bowl, beat the heavy cream on medium-high until it forms stiff peaks.
Set aside.
Blend the base: In a separate bowl, beat the softened cream cheese until smooth and fluffy, about 1–2 minutes.
Add flavor and sweetness: Mix in the powdered sweetener, lemon juice, lemon zest, vanilla, and salt. Beat until silky and no lumps remain. Taste and adjust sweetness or lemon juice as needed.
Fold gently: Using a spatula, fold the whipped cream into the lemon mixture in two or three batches.
Keep it light so the mousse stays airy.
Portion and chill: Spoon into small jars, ramekins, or glasses. Refrigerate for at least 1 hour, or up to 24 hours, to set.
Garnish and serve: Top with a dollop of whipped cream, a sprinkle of zest, or a few raspberries. Serve cold.