1. Rim the glass, if that’s your preference, with a mix of cocoa powder and super fine sugar. Use the creme de cacao as binder and dip into the cocao-sugar mix.
2. Add vodka, creme de cacao, creme de menthe into an ice-filled shaker and shake well.
3. Strain into the martini glass.
4. Garnish with a piece of dark chocolate and a sprig of mint and serve chilled.