Low Carb Buche de Noel (Yule Log) and Opera Cake

This recipe uses the Atkins Revolution Roll in another way: as a cake base. The filling is one that I adapted from UK Chef Gary Rhodes recipe in his book , Rhodes Around Britain.

Low Carb Yule Log (Buche de Noel)
For cake:
6 large eggs
6 tablespoons cream cheese
1 teaspoon vanilla extract
¼ teaspoon Cream of Tartar
1 pinch salt
Sugar substitute that is the equivalent of 1/3 cup granulated sugar.

Preheat oven to 350 degrees F. Butter a 15 inch jelly roll pan. Line the bottom with parchment paper and butter the parchment. Set aside.
Separate the egg yolks from the egg whites. Mix the egg yolks with the cream cheese, until well combined. Add the sugar substitute and mix well. Set aside.
Put the whites into a clean bowl. Add the cream of tartar and the salt. Beat until stiff peaks form (you can turn the bowl upside-down and the egg whites will stay put.)
Fold ¼ of egg whites into the yolk-cheese mixture, to lighten the batter. (. (If making the chocolate yule log, sift the ¼ cup of unsweetened cocoa over the batter at this point.) Then add the remaining egg whites and fold until the batter is light Do not over-fold.
Scoop the batter onto the prepared jelly roll pan. Gently push the batter into the corners and the sides. Avoid mashing the batter or stirring the batter because that will destroy the air bubbles and the cake won’t be as spongy and cake-like.
Bake for about 25-30 minutes or until a toothpick inserted into the cake comes out clean. Allow to cool completely. Run a knife along the edges of the pan to loosen the cake. Place a cutting board onto the cake pan and flip the pan over. Carefully remove the parchment paper from the cake. Then put the paper back on the cake and flip it over so that the top is on top. Trim the edges. Save the edges.

Filling:
½ cup heavy cream
1 teaspoon of vanilla extract, or rum extract or brandy extract
sugar substitute to the equivalent of ¼ cup sugar
4 ounces cream cheese, softened.

In a bowl, beat the cream cheese with the vanilla extract and sugar substitute until light and fluffy. Set aside.
In another bowl, whip the heavy cream until stiff. Fold the whipped cream into the cheese. Set aside.

Assemble:
Spread the filling on the cake. Break the edges onto the top of the filling, gently press in. Roll up. Wrap in plastic wrap and refrigerate at least 1 hour. Cut and serve.

Variation:
Chocolate Yule Log: sift ¼ cup unsweetened cocoa powder onto the batter and follow the recipe.
"Opera" Cake: follow the recipe for the cake. After baking, unmold it and trim the edges. Slice the cake into 3 equal pieces. Make the filling as directed. Spread a third of the filling onto the top of one cake piece. Top it with another piece. Spread half of the remaining filling on top. Cover with the final cake piece. Use the remaining filling to frost the top and sides of the cake. Fruit slices may be layered between the filling and the cake layers too.