Sift powdered sugar, powdered milk and cocoa into a bowl. Add fruit and toss until fruit is well coated. Stir in shortening and a few drops of vanilla. Mix thoroughly. Line an 8-inch square pan with plastic wrap. Pour mixture into pan. Refrigerate until firm. Turn out onto a board and cut into fingers. Wrap pieces in foil or pladtic wrap. Store in an airtight container in a cool place. Makes about 32 fingers.