I have long admired pretty yule logs that grace the covers of holiday cooking magazines. Beautiful rolled chocolate cakes with scrumptious fillings and decadent icings, adorned with meringue mushrooms and a fresh coating of snow. They look almost too perfect to eat. Almost. I have no problem digging into something pretty. I decided that this would be the year that I finally made a yule log, stumps and all! I had done two rolled cakes previously (see: Pumpkin Roll and Strawberries and Cream Angel Food Cake Roll), and was confident that I could churn out a pretty chocolate rolled cake without too many hiccups.
In addition to being pretty, I can’t imagine a more delicious yule log. The cake is rich and packed with chocolate flavor, which contrasts incredibly well with the espresso-mascarpone cream filling, and the chocolate ganache is literally the icing on the cake. I could eat it with a spoon!
You’ll notice that my cake is not a perfect spiral, which is due to it cracking in some spots when I rolled it up with the filling. The recipe calls for a 12×18 pan, and I used a 13×18 pan and baked it 8 minutes, which was too long, it definitely seemed done when I checked it. I would err on the very conservative side of baking times for this cake to ensure a soft, sponge-like cake that can be rolled easily.
I didn’t venture into the world of meringue mushrooms, but you could certainly add them if you wanted. This cake lends itself extremely well to any holiday flairs you want to add. I did a dusting of powdered sugar and some green sanding sugar. You could throw on green and red sprinkles, fondant holly and berries… there are so many fun possibilities.
If you’re looking for a show-stopping holiday dessert that tastes as good as it looks, this is it. Grab a fork and dig in!
Make the Dark Chocolate Ganache: Microwave the heavy cream and butter in measuring cup on high for 1½ minutes. Place the chopped chocolate in the bowl of food processor. With the machine running, gradually add the hot cream mixture through the feed tube and process until smooth and thickened, about 3 minutes. Transfer the ganache to medium bowl and let stand at room temperature for 1 hour, or until spreadable (the ganache should have the consistency of soft icing).
Make the Espresso-Mascarpone Cream Filling: Bring the heavy cream to a simmer in a small saucepan over high heat. Remove from the heat and whisk in the espresso and powdered sugar until dissolved; cool slightly. With a rubber spatula, beat the mascarpone in a medium bowl until softened. Gently whisk in the cooled cream mixture until combined. Cover with plastic wrap and refrigerate until ready to use.
Make the Cake: Adjust oven rack to upper-middle position and heat oven to 400 degrees F. Spray a 12x18-inch rimmed baking sheet with nonstick cooking spray, cover pan bottom with parchment paper and spray parchment with nonstick cooking spray; dust baking sheet with flour, tapping out excess.
Bring 2 inches of water to a simmer in a small saucepan over medium heat. Combine the chocolate, butter, and water in a small heatproof bowl and cover tightly with plastic wrap. Set the bowl over the pan of simmering water, reduce the heat to medium-low, and heat until the butter is almost completely melted and chocolate pieces are glossy, have lost definition, and are fully melted around edges, about 15 minutes. (Do not stir or let the water in the saucepan come to boil.) Remove the bowl from heat, unwrap, and stir until smooth and glossy. While the chocolate is melting, sift the cocoa powder, flour, and salt together in a small bowl and set aside.
In the bowl of a standing mixer, beat the egg yolks at medium-high speed until combined, about 15 seconds. With mixer running, add half of the sugar. Continue to beat, scraping down the sides of bowl as necessary until the yolks are pale yellow and the mixture falls in a thick ribbon when the beaters are lifted, about 8 minutes. Add the vanilla extract and beat to combine, scraping down the bowl once, about 30 seconds.
In a clean bowl with clean beaters, beat the egg whites and cream of tartar at medium speed until foamy, about 30 seconds. With the mixer running, add about 1 teaspoon of the remaining sugar; continue beating until soft peaks form, about 40 seconds. Gradually add remaining sugar and beat until whites are glossy and hold stiff peaks, about 1 minute longer. Do not overbeat. While the egg whites are beating, stir the chocolate mixture into the egg yolk mixture. With a rubber spatula, stir a quarter of the egg whites into the chocolate mixture to lighten it. Gently fold in the remaining egg whites until almost no streaks remain. Sprinkle the dry ingredients over the egg and chocolate mixture and fold in quickly but gently.
Pour the batter into the prepared pan; using an offset spatula and working quickly, smooth the surface and spread batter into pan corners. Bake until center of cake springs back when touched with finger, 8 to 10 minutes, rotating pan halfway through baking time. Cool the cake in pan on a wire rack for 5 minutes.
While cake is cooling, lay a clean kitchen towel over a work surface and sift 1 tablespoon cocoa powder all over towel. Run a paring knife around the edges of the baking sheet to loosen the cake. Invert the cake onto the prepared towel and peel off the parchment.
To Assemble the Yule Log: Starting at a long side, roll the cake and towel together into a jelly roll shape. Cool for 15 minutes, then unroll the cake and towel. Using an offset spatula, immediately spread mascarpone cream filling evenly over surface of cake, almost to edges. Reroll the cake gently but snugly around filling. Trim both ends of cake on diagonal and reserve.
Set the cake seam-side down on on a serving platter. Spread the ganache over roulade with a small icing spatula. Attach the reserved "stump" ends to the yule log using the ganache and spread ganache over them, as well. Use a fork to make wood-grain marks on the surface of the ganache before it has set. Refrigerate cake, uncovered, to slightly set the icing, about 20 minutes. Sift yule log with powdered sugar. The cake is best served the day it is made, but can be stored in the refrigerator, wrapped tightly in plastic wrap, for up to 3 days.