• Preheat oven to 400. Butter and line a 12 x 17-inch baking pan with parchment paper. Butter and lightly flour parchment; set aside. Lay a kitchen towel on top of a cooling rack and dust with icing sugar; set aside.
• Put egg yolks into the bowl of an electric mixer fitted with the whisk attachment; beat on high until pale yellow - 4-5 minutes. Transfer to a medium bowl and set aside.
• Put egg whites into the clean bowl of the electric mixer fitted with the clean whisk attachment. Beat on medium until soft peaks form, about 2 minutes. Raise speed to medium-high. Gradually add granulated sugar, and beat until stiff peaks form.
• Fold the egg yolks into the egg-white mixture. Sift cocoa powder and flour over the top and gently fold in, just until combined.
• Pour into the prepared pan and smooth with the top of an offset spatula.
• Bake until cake springs back when touched, 10-11 minutes. Run a knife around the side of the pan and invert the cake onto the prepared towel. Remove the parchment and dust with more icing sugar.
• Starting with a short-end roll cake in the kitchen towel, let cool completely seam side down on a rack.

Whipped Cream:

• Whip the cream on medium then to high until stiff peaks form then add 2 tbsp of icing sugar and a few drops of peppermint oil.
• Unroll the cake carefully. Using an offset spatula spread with about 2 cups of whipped cream.
• Reroll the cake, without the towel, and transfer seam side down to a serving platter. Store in the fridge for at least 30 minutes.

Chocolate Icing:

• Put melted unsalted butter in a clean bowl of the electric mixer fitted with the clean whisk attachment and add icing sugar and cocoa. Beat on medium for 2 minutes. Slowly ddd milk, vanilla , coffee if using and a pinch of salt.
• Spread the cake with chocolate icing to resemble the bark of a tree and sprinkle with icing sugar. Store in the fridge until you are ready to serve.