Preheat oven to 350°F and line a jelly roll pan with parchment paper.
In a bowl, beat the egg whites using a hand mixer until firm peaks are formed. Set aside.
In a separate bowl, beat the egg yolks with the sugar until the mixture whitens and becomes fluffy. Add the orange zest, the vanilla extract and gradually incorporate the flour.
Using a spatula, incorporate the egg whites into the egg yolks mixture. Perform very slow movements.
Pour batter into the prepared pan and spread into an even layer. The batter should be about 1 cm thick. Bake until top springs back when lightly pressed, 10-12 minutes.
Take it off the oven and let it cool down for 5 minutes. Invert the cake onto a clean kitchen towel slightly floured. Peel off parchment paper.
Starting at the short end, use the towel to tightly roll cake into a log (with the towel inside). Let it cool completely.
In a large bowl, beat together the heavy cream, the sugar, the instant coffee, and a pinch of salt, until soft medium peaks form. Refrigerate until ready to use.
Once the cake has cooled down, unroll it and spread about half of the filling evenly. Roll cake back into a log, using the towel to help create a tight roll. Place it on a long plate. Add the cocoa powder to the rest of the filling. Spread this chocolate frosting evenly over the log. Refrigerate until well chilled, at least 1 hour.
Decorate with cranberries, chocolate curls and rosemary.