Preheat oven to 120ºC . Grease and flour 2 cookie sheets. Combine the pistachios and chocolate pieces in a blender or food processor. Cover and whirl until very finely chopped. reserve. Beat together the egg whites and cream of tartar in a small bowl until soft peaks form. gradually add in sugar 1 tablespoonful at a time, until the mixture forms very stiff peaks. Fold in chocolate mixture and the vanilla. Using a teaspoon, drop small mounds of meringue onto the prepared cookie sheets, leaving about 3 cm between mounds. bake in the preheated oven for 30 minutes or until firm but not browned. Let stand for several minutes on cookie shets. Loosen the meringues carefully with a small knife, transfer the meringues carefully to a wire rack to cool completely. Store in a tightly covered container in a dry place. --