1️⃣ Prepare the sponge cake:

• Preheat your oven to 350°F (175°C) and line a 10×15-inch jelly roll pan with parchment paper.
• In a bowl, beat egg yolks and ¼ cup sugar until pale and thick. Add vanilla extract.
• In another bowl, beat egg whites with salt until soft peaks form. Gradually add the remaining ¼ cup sugar, beating until stiff peaks form.
• Gently fold the yolk mixture into the whites, then sift cocoa powder and flour over the batter, folding gently until combined.
• Spread the batter evenly in the prepared pan and bake for 10–12 minutes, or until the cake springs back when lightly touched.

2️⃣ Roll the cake:

• While the cake is still warm, carefully roll it in a clean kitchen towel dusted with powdered sugar. Let cool completely in the towel.

3️⃣ Prepare the buttercream:

• Beat butter until creamy. Gradually add powdered sugar, cocoa powder, vanilla, and heavy cream, beating until smooth and fluffy.

4️⃣ Fill and roll:

• Unroll the cooled sponge cake, spread an even layer of buttercream, then re-roll the cake tightly without the towel.

5️⃣ Make the ganache:

• Heat heavy cream until steaming. Pour over chopped chocolate and butter, letting it sit for 5 minutes. Stir until smooth.

6️⃣ Decorate the yule log:

• Spread ganache over the rolled cake, creating a bark-like texture with a fork. Decorate with powdered sugar, sugared cranberries, and rosemary sprigs.