Preheat oven to 350°F177°C.

Line a 15 x 11-inch (38 x 28 cm) baking sheet or jelly roll pan with parchment paper leaving excess paper over the edges to lift the cake out of the pan. If using a box cake mix, skip to step 9.

Beat egg whites with an electric mixer, set on high speed, in a large bowl until stiff peaks form.

Add the ½ cup sugar, one tablespoon at a time until stiff peaks form.

In a separate bowl, beat egg yolks and vanilla with an electric mixer set on medium speed for 3 minutes; gradually add the remaining sugar. Beat for 2 minutes or until thickened and lemon-colored.

Stir flour with cocoa, baking powder, baking soda and salt; gently fold the flour mix into egg yolk mixture alternately with coffee just until mixture is smooth..

Gently fold chocolate mixture into egg whites.

Spread batter evenly in prepared pan.

Bake for 15 minutes or until top springs back when touched lightly in the center.

Using the paper, gently lift the cake from the pan and onto a board or cooling rack.

Lay a clean linen towel over cake and a cooling rack or large cutting board on top and flip the cake onto the board so the towel is under the cake. Dust with powdered sugar so the cake doesn't stick to itself.

Optional: Cut a 1.5-inch piece from the end of the cake to make the 'branch' that you see in the pictures.

Immediately roll cake in towel starting at the narrow end. Place on a wire rack and cool completely.

While the cake is cooling, melt the 6 ounces chocolate in a microwave safe bowl in 20 second increments, stirring between until melted.

Take a large piece of parchment paper and spread a thin, even layer of the melted chocolate.

Roll the paper tightly and refrigerate.

Using an electric beater, whip the whipped cream and vanilla until it starts to thicken.

Add the powdered sugar in small amounts until the cream is thick.

Carefully unroll the cooled cake and cut off 1 inch strip from the long end of the cake for the extra branch.

Spread the whipped cream evenly onto the large and small cake pieces.

Roll both the large and small cakes with the seam-side down.

Cut the 'branch' at an angle so it sits flush against the cake.

Place both cakes on the surface where they will stay because once it's decorated it's very hard to move.

Remove the rolled up chocolate in parchment paper from the fridge.

Unroll the paper and the chocolate will break into bark pieces. Place in a bowl and refrigerate.

Once the cakes are placed, melt the chocolate in the same way as before in the microwave.

Working in small areas, spread a little of the 8 ounces of melted chocolate onto the log and place the chocolate bark pieces in a non-uniform manner until the entire cake and branch is covered.

Sprinkle lightly with powdered sugar to emulate snow.