Wash, drain 12 large mint leaves, and pat dry with paper toweling. Melt 2 tablespoons semisweet chocolate
morsels and 3/4 teaspoon solid-vegetable shortening in small heavy saucepan over low heat, stirring, until smooth. Repeat in a second saucepan, using 2 tablespoons white chocolate
baking morsels and 3/4 teaspoon shortening. Brush tops of 6 of the leaves with semisweet chocolate, and tops of remaining 6 with white chocolate. If chocolate hardens in pans, return to low heat, stirring. Set leaves aside to harden. Recoat. Carefully peel leaves from chocolate. Refrigerate until ready to use.