Bûche de Noël, a French tradition
The Bûche de Noël is a highly labor-intensive cake that French bakers make to celebrate the holiday season. There are many variations on this theme—different flavor profiles and cakes to use. In this slideshow I will demonstrate the technique involved with making a very classic, old-school Bûche de Noël.
Making mushroom meringues
Mushroom meringues are what most folks associate with this dessert. To make the caps, line a baking sheet with parchment (glue down the corners with a dab of the meringue) and pipe the French Meringue into shapes of caps and stems (use different sheets for each, since they bake at different rates). When piping caps, use a large, round piping tip and keep the tip close to the parchment until you've reached the desired circumference, then slowly lift to form a dome.
Piping mushroom stems
For the stems, pipe a base, then slowly squeeze as you lift the bag away, either straight up or at an angle. Don't worry about pointy tips, they will be filed down after baking.
Smoothing the caps
To remove any small points from piping, wet an offset spatula and use it to gently smooth points on the dome.
Sift the cocoa powder
To give the mushrooms a natural look, sift unsweetened cocoa powder over the tops with a fine strainer.
Bake, cool, and file
Bake the meringiues in a preheated 225°F oven with the convection fan turned off (leaving the fan on will put dents in your mushrooms). They will bake for between 1 1/2 - over 2 hours, depending on humidity, size, and shape. To test for doneness, remove a piece from the oven and allow it to cool for 10 minutes, then cut it open. if its completely dry in the center, the meringues are done. Allow them to cool for at least one hour, in a dry place, then file the points off the stems using a microplane.
Melt the chocolate
Melt the chocolate in a bowl set over a pot of boiling water, taking care not to expose the chocolate to water or steam, which will cause it to seize up. Bring the chocolate to 115°F, remove the bowl from the pot, and stir the chocolate well until the temperature comes down to 91°F. This is a "cheater" method of tempering that will prevent the chocolate from blooming or streaking.
Apply the chocolate to the caps
Using a small spoon, apply the chocolate to the back of the caps, aiming to make a circle with the chocolate that stops just before the edge of the meringue.
Adhere the stems
Place the caps upside down in egg containers and gently adhere the stems to the caps using the chocolate as glue. Allow the chocolate to set in a cool, dry place. Exposing the mushrooms to moisture will cause the meringues to melt and the chocolate to bloom and streak.
The mushrooms are great on their own; I love adding them to cookie plates for an unexpected, whimsical treat.
To assemble the cake, prepare the components
If you decide to go for it, making the full dessert requires a lot of planning and cooking of the seperate components. Before you begin, make sure that you have your filling(s) made and cooled, your buttercream made and whipped for use, your cake sponge baked with the parchment carefully removed, your soaker (simple syrup, with or without booze or flavoring) cooled and ready, and any decorations or melted chocolate ready to go.
Prepare and fill the cake
To begin, place the sheet of cake on a piece of parchment, then brush the cake with the soaker using a pastry brush on one side to make it pliable (do not "soak" the cake, just moisten it slightly). Then, spread your filling over the entire surface using an offset spatula. In the photo, I am applying chestnut pastry cream, somewhere between 1/8 and 1/4 inch thick. On top of this, I will sprinkle a thin layer of cranberry compote.
Make a roulade
Once you've spread the filling, begin to roll the cake up as you would a carpet. Aim to roll tightly, but don't use so much force that you tear the cake. Use the parchment underneath to tighten the roll as you go.
Cut the roulade
To create the knotty look, cut 1/3 of the roulade at an angle, then cut a short round off the end of the smaller piece, so you end up with a roll shaped like a small flat cylinder, and another round that is cut at an angle.
Frost the roulade
Place the large roulade on the plate that you will use to serve it, and frost it all over with a thick layer of the buttercream. Since this is a thick and rustic frosting, there is no need for a crumb coat.
Position the "branches"
Position the smaller, flat roulade perpendicular to the larger, frosted piece, then place the angled roulade so it is pointing out of the top.
Create the "bark"
Draw uneven lines in the buttercream to get a "bark" effect. Some people like to do this using a fork, but I prefer to use a small, offset spatula to draw lines and circles.
It's your choice how you decorate the cake. I like to draw accents by piping leftover melted chocolate. You may also decorate with berries, rosemary, candy, marzipan,and of course, meringues.
A winter wonderland
When decorating, feel free to scatter decorations around the plate, creating a snowy scene. The cake may be refrigerated before serving, but remember to only add the meringue decor right before serving, as it will melt in the fridge.