Place a large glass or metal bowl in the freezer to chill for about 20 minutes.

Add the Heavy Whip to the chilled bowl along with 3 tablespoons of the powdered sugar and a pinch of salt. Whip until medium peaks form, then remove 4 heaping tablespoons and place in a separate container.

Add the cocoa powder, the remaining 3 tablespoons of powdered sugar, and the vanilla to the remaining whipped cream and beat together. Begin at the lowest speed, increasing to medium speed, whipping until light and fluffy. Taste and add any additional sugar as needed.

Divide the mousse evenly between four short glasses. Place the mousse in the fridge alongside the additional whipped cream, to set for about an hour. When ready to serve, top each mousse with 1 tablespoon of the reserved whipped cream, some chocolate shavings.