01 - Combine milk and heavy cream in a small saucepan over low heat and warm until steaming without boiling.
02 - Add chopped dark chocolate and sugar, stirring constantly until fully melted and smooth.
03 - Stir in pure vanilla extract, then remove the saucepan from heat.
04 - Divide the hot chocolate mixture evenly among four small shot glasses.
05 - Optionally top each shot with whipped cream and a sprinkle of chocolate shavings or cocoa powder. Serve immediately.