Combine first 5 ingredients in a martini shaker. Cover with lid, and shake until thoroughly chilled. Remove lid, and strain into a chilled martini glass. Serve immediately. Garnish, if desired.
*1/2 teaspoon vanilla extract may be substituted.
Note: This recipe can be easily doubled. Make desired amount of servings, and store in a pitcher. Serve chilled. For testing purposes only, we used Smirnoff Vanilla Twist for vanilla vodka and Grand Marnier for orange liqueur.