Chill a martini glass
Rim the glass with chocolate syrup or cocoa powder, if desired
Fill a cocktail shaker with ice
Add 2 oz vodka
Add 1 oz chocolate liqueur
Add 1 oz cream or half-and-half
Add 1/2 oz Irish cream or coffee liqueur, if desired
Shake well until cold
Strain into the chilled glass
Garnish with chocolate shavings or a cocoa-dusted rim, if desired