Sprinkle the strawberry dust in an even layer over a saucer, moisten the rim of the glass then roll in the dust to coat.
Melt the chocolate in a heatproof bowl in 30 second bursts in the microwave then leave to cool slightly.
Pour the vodka and syrup into the bowl with the chocolate and stir until smooth.
Fill a cocktail shaker with ice, add the chocolate mixture then shake vigorously for 30 seconds.
Strain into the prepared glass. Garnish with a chocolate covered strawberry if you like, and serve.