Ingredients
Method
Step-by-Step
- Heat the oven to 350°F (175°C). Line one 10 x 15-inch jelly-roll pan with parchment paper and lightly grease the parchment.
- Whisk the egg yolks with about half of the granulated sugar and the vanilla until thick, pale, and ribbon-like.
- Sift the flour, cocoa powder, and salt together. Fold the dry ingredients gently into the yolk mixture.
- Beat the egg whites until foamy, gradually add the remaining sugar, and continue beating until medium-stiff, glossy peaks form.
- Fold the beaten egg whites into the batter in two or three additions, using a gentle motion so the mixture stays airy.
- Spread the batter evenly in the prepared pan. Bake for 12–15 minutes, until the cake springs back lightly and the edges just begin to pull away.
- While the cake is hot, dust a clean kitchen towel generously with confectioners' sugar. Invert the cake onto the towel, remove the parchment, and trim firm edges if needed.
- Starting at a short end, roll the cake tightly in the towel. Let it cool completely while rolled so the sponge sets its shape and is less likely to crack.
- Whip the cold heavy cream with the confectioners' sugar and vanilla until it holds medium-firm peaks.
- Carefully unroll the cooled cake and spread the whipped cream evenly over the surface, leaving about a 1/2-inch border. Roll it back up without the towel.
- Place the filled cake seam-side down on a serving platter and chill for at least 30 minutes.
- Heat the ganache cream until steaming but not boiling. Pour it over the chopped chocolate, let it stand for 2–3 minutes, then stir until smooth and mix in the butter if using.
- Cool the ganache until it is thick enough to spread, then frost the entire log. Drag a fork through the frosting to create bark-like lines.
- For a branch effect, cut a short diagonal piece from one end and attach it to the side of the log with ganache. Dust lightly with confectioners' sugar and decorate before serving.
Notes
Do not overbake the sponge; even 2–3 extra minutes can make it dry and prone to cracking. Roll it immediately after baking while it is flexible. Chill the finished cake before slicing, and keep leftovers refrigerated.
