Ingredients
Equipment
Method
Bake the cake
- Heat the oven to 350°F and coat a 10x15-inch jelly-roll pan with cooking spray; line it with parchment paper and lightly spray the parchment.
- Beat the egg yolks and 1/3 cup of the granulated sugar in a large bowl on medium-high until thick and pale, 3 to 4 minutes, then beat in the vanilla.
- Sift the flour, 4 tablespoons of the cocoa powder, baking powder, and salt over the yolk mixture, then fold until combined.
- In a clean bowl, beat the egg whites until foamy, then gradually add the remaining 1/3 cup granulated sugar and beat until glossy stiff peaks form.
- Fold one-third of the whites into the chocolate mixture to loosen it, then gently fold in the remaining whites.
- Spread the batter evenly in the prepared pan and bake for 10 to 12 minutes, until the top springs back when lightly touched.
- Dust a clean kitchen towel with the remaining 1 tablespoon cocoa powder, invert the hot cake onto it, and peel off the parchment.
- Starting at a 10-inch end, roll the cake up with the towel and let it cool seam side down for about 45 minutes.
Make the filling
- Beat the cold heavy cream in a large bowl until medium-firm peaks form.
- Gently unroll the cooled cake, spread the whipped cream over it leaving a 1/2-inch border, then roll it back up without the towel.
- Chill the cake seam side down for 30 minutes.
Make the frosting
- Melt the semisweet chocolate in a microwave-safe bowl in 30-second intervals, stirring between each, then let it cool until barely warm but still pourable.
- Beat the butter until creamy, gradually beat in the powdered sugar, then beat in the melted chocolate and milk until smooth and spreadable.
Assemble the cake
- Trim the ends of the cake, cut a 2-inch diagonal piece from one end, and place it against the side of the log to form a branch.
- Spread the frosting over the cake and mark it with fork tines to resemble bark.
- Chill the cake for at least 20 minutes before serving.
Notes
Roll the sponge while it is hot to help prevent cracking. Store covered in the refrigerator for up to 3 days; it can be frozen. For a dairy-free variation, use dairy-free whipping cream, butter, milk, and semisweet chocolate.
