Preheat oven to 350 degrees
Butter a 10x15in baking pan and line with parchment paper. Butter the parchment paper and put aside
Sift the cake mix into a bowl and mix in the salt
In the bowl with the egg yolks, add one teaspoon of the vanilla and beat the yolks. Add them to the cake mix and stir
Slowly add in the milk until a thick batter begins to form. You might not need to use the whole 2 cups, only enough to where the thick batter forms
In a stand mixer with whisk attachment, or with an electric hand mixer, beat the egg whites until stiff peaks form. One big spoonful at a time, fold the egg whites into the batter and slowly incorporate. Do not overwork the batter
Pour the batter into the pan and gently spread it until it is even. If there are any peaks visible, smoothly pass over them without pressing down
Place in middle rack in oven and bake for at least 15 minutes or until the cake is set and bounces back when lightly pressed
Coat a clean towel with powdered sugar. Make sure the towel is larger than the cake. Invert the cake onto the towel and remove the parchment paper. Fold the edge of the towel onto the short edge of the cake and slowly and carefully roll the cake. Allow it to cool. While the cake cools, make the buttercream
In a stand mixer with paddle adjustment, add both cheeses and stir on high for 10 seconds. Add the powdered sugar, 3 tablespoons of butter from the stick, the orange zest, and the remaining teaspoon of vanilla and whip on high until a smooth mixture forms. Remove half of the cream and place in a separate bowl. This will become the filling
In the leftover buttercream in the stand mixer, add the remaining stick of butter and the Nutella ™ and blend until smooth. This will become the frosting
Once the cake has cooled, carefully unroll it. Add the vanilla filling and spread it across the cake. Carefully roll the cake again.
Coat it evenly with the Nutella ™ frosting. Using a fork, draw lines across the cake to resemble bark. You may top with sprinkles, nuts, dried fruit, or just leave as is
Put in the fridge and allow to cool for at least an hour
Serve and enjoy!