Ingredients
Equipment
Method
Make the cake
- Heat the oven to 350°F.
- Line a 10x15-inch jelly-roll pan with parchment paper and coat the parchment and exposed sides of the pan with nonstick cooking spray.
- Beat the egg yolks with 1/3 cup granulated sugar in a large bowl until thick and pale, about 2 to 3 minutes.
- Mix in the vanilla.
- Sift the flour, cocoa powder, baking powder, and salt into the yolk mixture, then fold just until combined.
- In a clean bowl, beat the egg whites until foamy.
- Gradually beat in the remaining 1/3 cup granulated sugar until stiff, glossy peaks form, about 2 to 3 minutes.
- Fold the egg whites into the chocolate mixture in three additions until no white streaks remain.
- Spread the batter evenly in the prepared pan.
- Bake for 10 to 12 minutes, until the cake springs back when lightly touched.
- Dust a clean kitchen towel with 1/4 cup powdered sugar.
- Invert the warm cake onto the towel and peel off the parchment.
- Roll the cake and towel together from a short end, then cool seam-side down on a rack for 1 hour.
Make the ganache
- Heat 3/4 cup heavy cream in a small saucepan over medium heat until steaming.
- Pour it over the chocolate and let stand for 5 minutes.
- Stir smooth and mix in the butter.
- Cool for 45 to 60 minutes, stirring occasionally, until spreadable.
Make the filling
- Beat the remaining 1 1/2 cups heavy cream with the remaining 2 tablespoons powdered sugar until medium-stiff peaks form, about 2 to 3 minutes.
Assemble and decorate
- Gently unroll the cooled cake.
- Spread the whipped cream evenly over it, leaving a 1/2-inch border at the far edge.
- Reroll the cake without the towel and place it seam-side down on a serving platter.
- Refrigerate the cake for 30 minutes to firm the filling.
- Trim the ends, then cut a 2-inch diagonal piece from one end and attach it to the side of the log with a little ganache.
- Spread the remaining ganache over the outside and draw lines through it with a fork to resemble bark.
- Refrigerate for at least 1 hour before slicing and serving.
Notes
For a clean roll, shape the cake in the towel while it is still warm. Store covered in the refrigerator for up to 3 days; freeze yes, wrapped well for up to 1 month. For a dairy-free variation, use dairy-free whipping cream, chocolate, and butter.
