In a large mixing bowl, beat the heavy cream with an electric mixer until stiff peaks form.
In another mixing bowl, beat the cream cheese with the pumpkin puree, Erythritol, pumpkin pie spices, vanilla and salt, with the mixer until light and fluffy.
Fold the two mixtures together, gently.
Scoop the mousse into your serving bowls or glasses and refrigerate for at least 4 hours or overnight to set.
Serve cold, optionally topped with whipped cream, nuts and sprinkled with pumpkin pie spices.