
Line baking pan with parchment paper. Leave excess parchment paper hanging out sides of baking pan.
Prepare brownies according to instructions on box or in recipe of choice.
After removing baked brownies from oven, let brownies cool 10 to 15 minutes, then carefully and gently lift brownies out of baking pan using excess parchment paper. Let brownies rest on parchment paper until completely cooled.
Once brownies are completely cooled, cut sheet of brownies into 8 rectangles. Separate brownies slightly for easier decorating.
Sift confectioners' sugar into medium mixing bowl. Add light corn syrup, 3 tablespoons water, and charcoal powder (or 1 to 2 drops black food coloring). Whisk vigorously until ingredients are well combined. Note: mixture will be very thick.
Add more water in ½ tablespoon increments, whisking well between each addition, until icing mixture is smooth but still thick. If usign
To test for ideal icing consistency, lift small amount of icing out of bowl with whisk. Hold whisk over bowl and let icing drizzle back into bowl. Consistency is ideal when drizzled icing remains on surface of icing in bowl for 2 to 3 seconds before melting back into icing.
Scrape icing into piping bag fitted with small tip, into plastic zippered bag, or into squeeze bottle. If using plastic zippered bag, gently press icing toward one corner of bag, then twist or tie bag closed, removing as much air as possible. Snip very small piece of corner off bag to create small piping hole.
Working one-by-one, pipe icing onto brownies to resemble Hocus Pocus spellbook. Start by piping two side-by-side vertical rows down left edge of brownie to create book spine. Next, pipe dime-sized dot in middle of right edge of brownie, to create spot for eye. Last, pipe 3 curvy lines coming off of book spine or eye in organic shapes to resemble book's stitches.
While icing is still soft, gently press candy eye into icing dot. Let icing dry 2 to 3 minutes, then pipe hash marks across curved stitch lines to complete stitches.
Repeat process until all brownie books have been decorated. Let icing dry completely before stacking or serving brownies.