Chill your bowl and beaters: Place your mixing bowl and beaters in the freezer for 10 minutes before starting.
Whip the cream – Add heavy cream to the chilled bowl and beat until soft peaks form.
Add peanut butter and sweetener – Gently mix in the peanut butter, powdered erythritol, vanilla extract, and pinch of salt.
Beat until fluffy – Continue beating until the mixture is light and fluffy. Do not overmix.
Taste and adjust – Taste the mousse and adjust sweetness if needed.
Chill before serving – Spoon the mousse into ramekins or cups and refrigerate for at least 30 minutes.
Serve – Garnish with sugar-free chocolate shavings or crushed nuts if desired. Enjoy!