This is an easy chocolate bark that is a great alternative to the traditional buttercream icing scored with a fork and commonly used to decorate a bûche de Noël (yule log). It lends a more contemporary look to your design and requires no special equipment. I recommend using couverture chocolate, such as Valrhona, to ensure a fluid consistency for easy spreading.
This makes enough to cover a büche de Noël 7 to 8 inches long, with a few extra pieces left over.
Cut off the zipper closure of a gallon freezer bag, cutting all the way across the top of the bag. Cut the bag down the side seams and lay the bag open flat on a work surface. Cut the bag in half along the bottom seam; you now have two flat square sheets of plastic. Lay the sheets side by side on a flat work surface. Very gently melt 2 1/2 oz/71 g of dark chocolate (preferably 55% to 66% cacao) in a double boiler or water bath. Stir the chocolate frequently, paying attention to the bowl's temperature so that the chocolate does not overheat. The goal is to melt the chocolate just below body temperature. You never want the chocolate to feel hot; it should only be warm enough to melt it slowly, which can take several minutes to complete. (Take care not to splash even the smallest amount of water into the chocolate. A microwave is okay, too, but watch the temperature even more closely and stir it frequently.)
Once the chocolate is fully melted, wipe off any water from the bottom of the bowl, and, working quickly, immediately scrape the chocolate out onto one of the sheets of plastic and spread it out thinly and evenly using a small offset spatula to about 1” from the edge of the sheet; try to avoid creating spots that are too thin (you should not be able to see the plastic through the chocolate layer). As soon as the chocolate is spread out, immediately and carefully place the second sheet on top, ensuring the edges of the two sheets are well aligned so that all the chocolate is covered. Press lightly to ensure the top plastic sheet is adhered to the chocolate. The chocolate is now sandwiched between the two sheets. Immediately (before the chocolate sets) flip the packet over and gently roll it up into a tube about 2 inches in diameter. Place the tube on a plate or tray and clip it closed with a paper clip, or slide it into the cardboard tube of an empty roll of paper towels. Refrigerate until completely set.
Once the chocolate is fully set, place the roll on a flat work surface and gently unroll it using the edge of your palm to push it outward (do not crush it) until it unrolls completely; the chocolate sandwiched inside will crack and break lengthwise as you unroll it, which is desired. Carefully peel off the top plastic sheet to reveal the long pieces of broken chocolate bark; their edges will curl slightly upward. If needed, run a small offset spatula under the chocolate pieces to release them from the bottom plastic sheet. For any strips that are too long for your cake, you can carefully break them using your fingers to trim their length. Transfer the strips to a tray or plate and keep them cool until needed. When decorating your büche de Noël with them, carefully place the strips, curled ends up (to look like peeling bark) onto the cake with a crumb coat to ensure the strips adhere. Dust the bark with a little cocoa powder and/or confectioners’ sugar, if desired.
Chef Zach’s Notes:
I prefer Valrhona Equatoriale 55% cacao for this.
A wine cabinet is one of the best places to store chocolate décor for later use. Stored at a constant cool temperature, your chocolate décor pieces will last months.
This method of melting chocolate at the lowest possible temperature is one way to avoid full tempering and is a good choice for small décor pieces because it is much faster. If you accidentally overheat your chocolate and it sets with a little bit of splotchy white bloom, use a dusting of cocoa powder or confectioners’ sugar to cover up the imperfections.