Prepare his cocktail by pouring the vanilla vodka and hazelnut liqueur into a rocks glass over ice. Pour the contents of the glass into a cocktail shaker, then pour back into the rocks glass to mix. Prepare her cocktail by pouring the raspberry vodka and creme de cacao into a cocktail shaker over ice. Cover, and shake until the outside of the shaker has frosted. Strain into a martini glass rimmed with chocolate syrup, pour in the half-and-half, and garnish with maraschino cherries. Kiss to mix flavors.