To make the cake
Preheat your oven to 220°C / 425°F and line a baking sheet pan with parchment paper. Cut a slit in the parchment paper in each of the four corners of the pan so that the parchment paper lies completely flat against the edges of the pan. Set aside.
Drop the egg whites into the bowl of a stand mixer. Whisk on high speed for about 2 to 3 minutes, until wet, soft peaks form. Set aside.
In a large bowl, whisk the egg yolks and sugar together until they’re pale yellow. In a separate, smaller bowl, sift the cocoa powder, all- purpose flour, coffee granules, baking powder, and salt together. Add these dry ingredients to the bowl containing the egg yolks and sugar. Whisk to combine – batter will be VERY thick and hard to mix, but this is normal, so just try your best to mix everything together.
Add in half of the egg whites and use a rubber spatula to gently fold the whites into the batter. Continue by adding the remaining half of egg whites and, this time, be very gentle when folding the whites into the batter with your spatula; make light, long folds.
Pour the batter into you’re prepared pan and use your spatula to gently smooth out the batter. Bake the cake for 6 to 7 minutes, or until the cake springs back when gently pressed by the tip of your finger (for me, it’s always about 6 1/2 minutes in the oven). Let the cake slightly cool in the pan for 2 minutes – no longer.
Dust a clean kitchen towel with powdered sugar and invert warm cake onto towel. Peel off parchment paper.
Starting at the short end, use the towel to tightly roll cake into a log. Let cool completely.
To make the white chocolate filling
Using a hand mixer or a stand mixer fitted with a whisk attachment; whip the 250 gr. of cold heavy cream into stiff peaks on medium-high speed, about 2½ -3 ½ minutes. Set aside.
Melt white chocolate and 50 gr. of heavy cream in a medium-size, heat proof bowl; set over a saucepan of barely simmering water, when melted, remove from the heat and allow to cool for few minutes.
Carefully fold melted chocolate mixture with whipped cream. Store in refrigerator for at least 1 hour.
To make the chocolate frosting
Using a hand mixer or a stand mixer fitted with a whisk attachment; whip the 300 gr. of cold heavy cream into soft peaks on medium-high speed, about 2-3 minutes. Set aside.
Melt dark chocolate and 50 gr. of heavy cream in a medium-size, heat proof bowl; set over a saucepan of barely simmering water, when melted, remove from the heat and allow to cool for few minutes.
Carefully fold melted chocolate mixture with whipped cream. Store in refrigerator for at least 1 hour.
To assemble the cake
When cake is cool, unroll and spread filling evenly over cake. Gently roll the cake back up just like you did before (minus the towel). Place seam side down on a baking sheet and refrigerate until well chilled, 1 hour.
Cut a thick diagonal slice from one end of the log. Lift the log on to a plate, then arrange the slice on the side with the diagonal cut against the cake to make a branch. Spread the chocolate frosting over the log and branch (don’t cover the ends), then use a fork to mark the icing to give the effect of tree bark. Decorate with chocolate barks (if using), raspberries, spearmint leaves and powdered sugar to resemble snow.
***How to make chocolate bark decoration
Add 120 gr dark chocolate to a microwave-safe bowl in pieces. Microwave for 30 seconds and stir. Repeat until fully melted.
Lay a sheet of parchment paper 14 x 16 inch ( 35 x 40 cm) on a flat surface. Spread a thin, even layer of chocolate over the paper. Take the edge of paper closest to you and roll over the chocolate, making sure that no chocolate is touching. Refrigerate for at least 30 minutes, then unroll. I recommend wearing food safe latex gloves and work quickly when handling the bark, as the heat from your hands will melt the chocolate.
