Instructions

For the Chocolate Sponge

Follow the directions on Joy of Baking to the letter. They are as follows, and I paraphrase:

1. Preheat oven to 350Fwith a rack in the center.
2. Spray with a nonstick vegetable spray, a half-sheet pan or jelly roll pan. 
3. Line the pan with parchment paper and then spray the paper and liberally dust cocoa powder all over the parchment. This will help keep your cake from sticking.
4. While the eggs are still cold, separate the eggs, placing the whites in one bowl and the yolks in another. Cover with plastic wrap and bring to room temperature before using (takes about 30 minutes). 
5. Meanwhile melt the chocolate on medium heat in a microwave oven, stirring after every 30-second burst. Let the chocolate cool to room temperature.
6. In the bowl of your electric mixer (or with a hand mixer) place the egg yolks, heavy pinch of salt, and half of the sugar until it is thick and billowy, about 5 minutes. Make sure it gets to the "ribbon stage" where the batter sits on the surface for a few seconds before sinking back in. Beat in the vanilla extract.
7. Add the melted chocolate and fold to combine evenly. Set aside while you beat the egg whites.
8. In a clean mixing bowl, with the whisk attachment, beat the egg whites until foamy. Add the cream of tartar and beat at medium-high speed until soft peaks form. Beat in the rest of the sugar and take the whites to stiff peaks.
9. Gently fold a small amount of the egg whites into the egg yolk mixture using a rubber spatula or whisk to lighten the batter. 
10. Fold in the remaining whites just until incorporated.  Fold gently so you don't deflate the batter. Spread the batter evenly into the prepared pan with an offset spatula. Bake until the cake is puffed, has lost its shine, and springs back when gently pressed, about 15 - 17 minutes. Remove from oven and place on wire rack to cool. Cover the cake with a clean, slightly damp towel.

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For the Cran-Raspberry Mascarpone Cream

1. Whip the heavy cream along with sugar (to taste) and a pinch of salt until thickened.
2. Whip in the mascarpone cheese. Just plop it in there. If you're using the whip attachment on your stand mixer, I promise it will all come together. If you're using a hand mixer, plop the beaters right on top of the blob of cheese to break it up and then mix away.
3. Your cream and cheese mixture will whip up quickly at this point, so be careful not to overwhip. The cheese can turn grainy and gross, so just take it to medium peaks.
4. Plop in the cranberry sauce and chopped raspberries and whip for 2-3 seconds to get it going, then fold in by hand so there are no streaks.

To Assemble the Roll

1. Leave your cooled cake in the pan and remove the towel.
2. Spread the filling evenly over the cake, from edge to edge. Leave about 1 1/2" plain at one short end, but cover the rest with an even coat. Reserve about 3 Tablespoons of the filling.
3. Using the parchment to help you, roll the cake up starting from the short end and rolling towards the end that you left plain. Carefully peel back the parchment as you roll. That initial roll may very well crack, but it's in the middle, so don't worry too much about it. Mine cracked about 1 1/2" in, but whatever. Keep rolling and peeling back the parchment until he's all rolled up. Move the roll to a cutting board, seam side down. Have your Presentation Platter ready too. Cover it with some strips of waxed paper so you don't make a mess on the platter. You'll carefully pull those pieces out before the final garnishing.
4. Trim one end of your jelly roll at an angle. You can make this piece as large or as small as you want, but for aesthetics, I wouldn't make it any more than 1/2 of the length of the remaining roll. Set that guy aside for a moment.
5. Place the longer part of your roll on the serving platter. Slather the remaining filling mixture on the angled end of the piece you just cut off and then stick it to the roll wherever you want. The reserved mixture will act as glue, so press it together fairly well without squishing your cake.
6. Cover loosely with plastic wrap and refrigerate.

For the Ganache

1. Bring the cream just to a boil and then remove from the heat.
2. Pour in the chopped chocolate all at once and stir until emulsified--rich, thick, dark and shiny.
3. Refrigerate until it's the consistency of frosting. You don't want it to be runny.

To Make the "Bark"

1. Once the ganache is at spreading consistency, remove the cake from the fridge.
2. Using a small offset spatula (because it's easy to use, but use what you have), spread a thin coat of ganache all over the roll and down to the waxed paper. Try not to leave any of the roll naked. But if you have to, cover it with whipped cream later!
3. Once the ganache is spread evenly. Drag the tines of a fork back and forth over it until it looks as barkish as you want.
4. Refrigerate until the ganache is set. You'll be able to tell because it will no longer be shiny.

To Garnish

1. Using a serrated knife, carefully trim off the very ends of your jelly roll so there's no sloppy filling sticking out.
2. Carefully remove the strips of waxed paper from around the cake roll. You may have to hold the cake in place with a spatula while you pull. Just go slowly and get rid of all the waxed paper.
3. Liberally dust the cake with powdered sugar. Some of it will dissolve as it sits, so use more than you think you need.
4. Whip your cream to stiff peaks (I use cream, a touch of sugar, a pinch of salt and a little bit of vanilla). I think I whipped about 3/4 cup to garnish mine. Make as much or as little as you want.
5. Apply your whipped cream artfully around your Yule Log.
6. Press sugared cranberries and raspberries wherever you think they should go.
7. Some edible (or at least non-toxic) greenery would be lovely as well.
8. Before presenting, dust the entire thing--platter and all--with some more powdered sugar.