Beat softened cream cheese on medium speed until completely smooth and fluffy, about 2 minutes.
Add powdered sugar, salt, vanilla extract, peppermint extract, and sour cream.
Beat until silky and fully incorporated.
In a separate chilled bowl, whip heavy cream to medium peaks. The cream should hold its shape while still looking smooth and soft.
Fold whipped cream gently into the cream cheese mixture in two additions using a silicone spatula.
Fold in crushed candy canes and shaved dark chocolate just until evenly distributed.
Avoid overmixing to preserve the mousse texture.