Preheat the oven to 350° and prep a 17x12 inch rimmed baking sheet by spraying it with non-stick baking spray and lining it with parchment paper. Be sure to let the parchment paper have at least a 1-inch overhang on all sides. Spray the parchment lightly with the non-stick baking spray.
In a medium bowl whisk together the flour, cocoa powder, baking powder, instant coffee, and salt. Set aside.
In a large bowl whisk together the egg yolks and sugar until well combined and light in color. Add in the sour cream, butter, and vanilla extract and whisk until combined. Fold in the dry ingredients until just combined.
In another bowl whip the egg whites until stiff peaks form. Fold 1/3 of the whipped egg whites into the batter until combined and then add the rest and fold until just barely combined and no white streaks remain.
Spread the cake batter evenly into the prepared pan and bake for 10-12 minutes, until the center of the cake springs back when gently pressed on.
Let the cake cool for just about 2 minutes. Meanwhile prepare a clean kitchen towel by dusting it lightly with powdered sugar. Once the cake has cooled for 2 minutes and is still pretty hot, run a knife around the edges and then very carefully and quickly turn the cake out onto the kitchen towel. Carefully and slowly peel back the parchment paper from the cake, making sure not to tear the cake at all. Dust the cake with more powdered sugar.
Starting from the short end, use the towel to roll the warm cake snuggly so the towel is being rolled up inside it. Place the towel with the cake’s seam side down and let it cool completely, about an hour.
Add the softened cream cheese and powdered sugar to the bowl of a stand mixer and use the whisk attachment to mix at medium speed for about 1 minute. Remove to a small bowl and set aside.
Add the heavy cream and vanilla to the stand mixer and whip on high speed until medium-soft peaks form. Add the cream cheese mixture and whip on medium until creamy and fluffy. Set aside until you’re ready to assemble your cake.
Place the chocolate in the bowl of a mixer. Heat the cream in the microwave until steaming but not boiling, about 1 minute. Pour the hot cream over the chocolate and let it sit for a few minutes. Use a whisk to combine the chocolate and cream.
Let the ganache cool to room temperature, or chill in the fridge for about 20 minutes. Using the mixer and the whisk attachment, whip the cooled ganache on high speed for about 3-4 minutes, until light in color and thick and fluffy.
Gently unroll the cake from the kitchen towel. Make sure none of the cake sticks to the towel as it’s unrolled.
Spread the whipped cream filling evenly over the cake, leaving a/4 inch border around the edges. Re-roll the cake using the towel to help roll it. Cover the cake tightly with plastic wrap and refrigerate for at least 1 hour, up to overnight before frosting.
When you are ready to frost the cake, remove it from the fridge and unwrap the cake. Cut off about 3 inches of one end of the cake at a sharp angle to use as a branch. Place the branch on one side of the cake with the angled edge against it.
Spread the whipped ganache all around the cake, smoothing with a frosting spatula. You can use a fork or the frosting spatula to give the ganache a bark-like texture.
Dust with powdered sugar and decorate with rosemary or thyme and sugared cranberries.