Make the Cake

Preheat the oven to 375°F (190°C) and butter an 11x17 (28x43 cm) jelly roll pan. Line with parchment paper, then butter and flour the parchment paper. Set aside.

In the bowl of a stand mixer fitted with a whisk attachment (or with a medium bowl and handheld electric mixer) whip the egg whites on medium-high to soft peaks.

Add ¼ cup (2 oz/57 g) sugar, one tablespoon at a time and continue to whip to stiff, glossy peaks. Transfer the whipped whites to a clean bowl.

To the bowl used for whipping the whites, add the egg yolks and the remaining ½ cup (4 oz/115 g) of sugar. Whip on high speed until the yolks are thick and pale, about 4 minutes.

In a small bowl, sift together the flour, cocoa powder, baking powder, baking soda and salt, then switch the mixer to low speed and mix the flour mixture into the yolks.

With a metal spoon, fold in ⅓ of the whipped whites into the yolk mixture to lighten the batter, then gently fold in the remaining whites until fully mixed.

Spread into the prepared pan and bake for about 10 minutes until puffed and set. The cake will spring back when pressed and a thin knife inserted in the center will come out clean.

Sift a generous amount of powdered sugar all over the hot cake, then place a clean tea towel over the cake. Place the bottom of another baking sheet or jelly roll pan on top of the tea towel, and then holding both pans, flip them so the pan with the cake is on top.

Lift up the pan to gently release the cake, then very gently peel off the parchment paper.

Starting with a long end, roll up the cake with the tea towel and let it cool in the shape.

Assemble the Cake

Unroll the cake and spread on a thick layer of Vanilla Buttercream.

Reroll the cake (without the towel).

Cut a 10-inch (25 cm) piece of the roll and place it, seam side down, on an oval serving plate. Trim the ends, if necessary, to make them look nice.

Spread the roll with a generous layer of Chocolate Buttercream, leaving the ends exposed.

Cut the remaining roll of cake in half and using the chocolate buttercream to help attach, place one piece upright on top of the log and the other piece on one side of the log. Spread more chocolate buttercream on the attached piece to make it look like one log.

Decorate the plate and cake with Meringue Mushrooms or even cranberries, sprigs of rosemary or whatever else festive that you have on hand.

This is best served the day it is made. Store leftovers in an airtight container at room temperature for 2 days.