Prep the berries. Rinse and pat dry.
Slice strawberries if using. Toss berries with lemon juice and a little sweetener if needed. If you like a thicker sauce, sprinkle in chia seeds and let sit while you make the filling.
Whip the cream. In a chilled bowl, beat the cold heavy cream to soft peaks.
Don’t overbeat. Set aside.
Beat the cream cheese. In a separate bowl, beat softened cream cheese until smooth and fluffy, 1–2 minutes. Add powdered sweetener, vanilla, lemon zest, and a pinch of salt.
Beat until creamy with no lumps.
Fold together. Gently fold the whipped cream into the cream cheese mixture in two batches. Use a spatula and light strokes to keep it airy. Taste and adjust sweetness.
Assemble. Spoon the cream cheese mousse into small jars or a serving dish.
Top with the berry mixture. For a layered look, alternate mousse and berries.
Chill. Refrigerate for at least 30–60 minutes to set and meld flavors. It firms up slightly and tastes even better cold.
Serve. Garnish with a few whole berries or a light dusting of sweetener.
Enjoy straight from the fridge.