Place the martini glasses on a designated, flat shelf in the freezer for 10 minutes.
Using a serrated knife, cut shavings off the block of chocolate and reserve for later.
Fill a cocktail shaker with ice. Pour the vodka, chocolate liqueur and Irish cream over the ice. Put top on the shaker and shake firmly.
Carefully pull out the glasses from the freezer taking care not get finger marks on the body of the glass. Pour into the chilled glass. Garnish with chocolate shavings in the middle and serve.