Combine cocoa powder and sea salt on a small plate, then rim a chilled martini glass by moistening the edge with water and dipping into the mixture.

Fill a cocktail shaker with ice cubes and add the vanilla vodka, chocolate liqueur, crème de cacao, and heavy cream.

Shake vigorously for 15-20 seconds until the mixture is well-chilled and frothy.

Strain into the prepared martini glass and garnish with chocolate shavings on top before serving immediately.