Step 1Crush the coffee beans with a mortar and pestle. Set aside.
Step 2In a small saucepan, combine one-half cup water and one-half cup sugar. Heat until the sugar dissolves. Add the seeds from the vanilla bean. Whisk to break up the vanilla seeds. Let cool.
Step 3Fill a cocktail shaker with ice. Add the crushed beans, the rum or bourbon, 1 tablespoon of the vanilla simple syrup and the half and half. Shake and strain (use a very fine mesh strainer to remove bean grains). Serve in a chilled martini glass.