In 1-quart saucepan, melt semisweet chocolate with shortening over low heat, stirring occasionally. Drizzle glaze in horizontal parallel lines about 1 inch apart over top of brownies. Immediately draw knife through glaze in straight vertical lines to form pattern. Refrigerate until firm, about 15 minutes. For brownies, cut into 9 rows by 4 rows. Cover and refrigerate any remaining brownies.