Bûche De Noël (A French Christmas Dessert)

Instructions

• Make the chocolate sponge cake: Preheat the oven to 350°F (180°C). Grease a roll cake baking pan or 18 x 13-inch (45 x 33 cm) baking sheet with nonstick spray and line with parchment paper.
• In a large bowl, whisk together the egg yolks and 3 tablespoons of sugar until the sugar is dissolved.
• Whisk in the milk, vegetable oil, and vanilla until smooth. Sift in the flour, cocoa powder, and cornstarch and whisk until smooth.
• In a large bowl with an electric hand mixer, or the bowl of a stand mixer fitted with the whisk attachment, whip the egg whites on medium speed until frothy, about 2 minutes. Add the cream of tartar and whip on medium-low speed for 2 minutes, then gradually add the remaining ½ cup (100 G) superfine sugar. Whip on medium-high speed until stiff peaks form, another 2–3 minutes.
• Fold the egg white mixture into the egg yolk mixture until just combined, taking care not to overmix.
• Spread the batter evenly on the prepared pan. Bake for 12–15 minutes, until fluffy and the cake springs back when gently pressed.
• Drape a kitchen towel over the cake and set a wire rack on top. Carefully invert the cake onto the rack, peel back the parchment from the bottom, and let cool for 10 minutes. Carefully roll the cake into a log with the towel inside and allow to cool completely.
• While the cake cools, make the chocolate hazelnut buttercream: In a large bowl, beat the butter and powdered sugar with an electric hand mixer on low speed until combined. Increase the speed to high and whip for 2–3 minutes, until light and fluffy.
• Reduce the speed to low and add the milk, vanilla, and salt. Whip again for 2–3 minutes until well incorporated and the buttercream is light, bright white, and fluffy.
• Fold in the chocolate-hazelnut spread with a rubber spatula. Cover with a kitchen towel or place wrap and set aside at room temperature.
• Make the ganache: Place the chopped chocolate in a medium bowl. Pour the hot cream over the chocolate. Stir until the chocolate is melted. Refrigerate the ganache for at least 30 minutes to firm.
• Make the meringue mushrooms: Reduce the oven temperature to 200°F (93°C). Line a baking sheet with parchment paper.
• In a medium bowl, beat the egg whites and cream of tartar with an electric hand mixer until soft peaks form, about 3 minutes.
• Gradually add the sugar and whip until dissolved and stiff peaks form, about 2 minutes more. The mixture should be glossy, shiny, and very stiff.
• Transfer the mixture to a piping bag fitted with a medium round tip. Pipe half of the meringue onto the prepared baking sheet in ½–1 inch (2.54 cm) wide circles resembling mushroom caps. Use your fingers to gently press down any peaks. Pipe the remaining meringue into ½–1 inch (2.54 cm) long stems. Dust the mushrooms with cocoa powder.
• Bake for 1½–2 hours, until the mushrooms are completely dried and hard to the touch. Turn off the oven and leave the mushrooms dry out in the oven for at least 30 minutes, or up to overnight. The mushrooms can be made 1-2 days ahead.
• Assemble the mushrooms: Dip the flat sides of the mushroom caps in the melted chocolate and attach the mushroom stems. Stand the mushrooms upright and let dry, 30–45 minutes.
• Make the sugared cranberries and rosemary: Line a baking sheet with parchment paper and top with a wire rack.
• In a small saucepan, combine 1 cup (200 G) sugar and the water. Bring to a boil, whisking to dissolve the sugar. Drop the cranberries into the syrup and stir to coat, then remove with a slotted spoon and transfer to one side of the wire rack. Let cool for at least 1 hour, until no longer sticky, then sprinkle cranberries with ¼ cup (25 G) sugar. Set aside.
• Bring the remaining syrup to a boil. Add the rosemary sprigs and stir to coat, then remove with a slotted spoon and transfer to the other side of the wire rack. Let cool for at least 1 hour, then sprinkle rosemary with the remaining ¼ cup (25 G) sugar. Set aside.
• Assemble the bûche de noël: Unroll the sponge cake.
• Spread 2 cups (230 G) of the chocolate-hazelnut buttercream. evenly over the cake, leaving a 1-inch (2.54 cm) border around all sides.
• Starting from one end, using the towel to help guide the rolling, roll the cake into a tight spiral. Place the cake, seam-side down, in the refrigerator to set, at least 30 minutes, or up to overnight.
• Unwrap the cake log from the towel and set on a serving platter.
• Remove the ganache from the fridge and transfer to a piping bag fitted with a medium star tip.
• Trim 2½ inches (6 cm) ( off one end of the cake log and attach to the center of the log with 2 tablespoons of the ganache to resemble a stump.
• Cover the entire log, starting at one end and piping lengthwise, with ganache.
• Arrange the sugared rosemary and cranberries and meringue mushrooms around the log. Dust with powdered sugar to resemble snow.
• The cake will keep in the refrigerator, covered, for up to 3 days.
• Slice and serve.
• Enjoy!