1. For the Sponge Cake: Preheat the oven to 170°C (340°F). Beat the egg whites until stiff peaks form, gradually adding half of the sugar. Whisk the egg yolks with the remaining sugar. Mix the two preparations by gently folding and turning the mixture, then incorporate the flour mixed with almond powder in the same way. Spread the batter on a baking sheet lined with parchment paper. Smooth it out before baking the sponge cake for 10 minutes.
2. While the Sponge Cake is baking, prepare the Vanilla Cream. Begin whipping the cream with the mascarpone, then incorporate the sugar mixed with Chantifix and vanilla flavoring while whisking until the mixture is fluffy and firm. Place in the refrigerator for 20 minutes.
3. Meanwhile, prepare the Soaking Syrup: Boil the sugar with water. Off the heat, add the vanilla flavoring and rum. Remove the baking sheet from the oven, place a sheet of parchment paper on the sponge cake, flip the baking sheet to unmold. Brush the sponge cake with syrup, then roll it up with the parchment paper. Let it cool for 30 minutes.
4. For the Chocolate Ganache: Heat the cream in a saucepan, then off the heat, add the chocolate chips. Let it melt for 30 seconds, then whisk until smooth. Set aside.
5. Assembly: Spread the vanilla cream over the entire surface of the cooled sponge cake. Sprinkle with dark chocolate chips and/or crumbled toasted sliced almonds. Gently roll up the sponge cake. Secure the shape with the parchment paper. Place your Yule Log in the refrigerator for 1 hour.
6. Finishing Touches: Coat the entire surface of your Yule Log with thickened ganache. Trim the ends neatly. Decorate the cake, then refrigerate for a minimum of 2 hours or until ready to transfer to the serving platter.