Beat egg whites with one Tbsp. erythritol with an electric mixer until stiff peaks form.
In a separate mixing bowl, beat the heavy cream with remaining Tbsp. erythritol until soft peaks form. Set aside 4 Tbsp. of this whipped cream to decorate the finished mousse cups.
In another large mixing bowl, mix the Keto Chow into the milk, then mix in the lemon zest and lemon juice.
Fold 1/3 of the remaining whipped cream into the Keto Chow mixture to lighten it. Then fold in the rest of the whipped cream.
Fold in the egg whites in two parts. The mousse should be light and fluffy. It’s okay if you still see white streaks.
Place a quarter of the berries into each serving dish and add the lemon mousse. Top each one with the reserved whipped cream.
Garnish with berries and mint leaves if desired.
Cover loosely, and chill at least one hour for best flavor and texture.
These will keep tightly covered in the fridge for up to three days but are at their best within 24 hours.