For the Sponge Cake:

1. 1. Preheat your oven to 350°F (175°C). Line a jelly roll pan (approximately 15×10 inches) with parchment paper and lightly grease it.
2. 2. In a mixing bowl, combine flour, cocoa powder, sugar, and eggs. Beat on medium speed until smooth and well blended—about two minutes.
3. 3. Pour the batter into the prepared pan and spread it evenly. Bake for about 12-15 minutes or until a toothpick inserted comes out clean.
4. 4. Once baked, remove from the oven and let cool slightly before rolling up with parchment paper while still warm.

For the Whipped Cream Filling:

1. 5. In a bowl, whip heavy cream until soft peaks form. Gradually add powdered sugar while continuing to whip until stiff peaks form.
2. To Assemble the Yule Log:
3. 6. Carefully unroll the cooled sponge cake. Spread an even layer of whipped cream over its surface.
4. 7. Roll it back up tightly without parchment paper. Transfer seam-side down onto a serving platter.
5. 8. Dust generously with powdered sugar before serving.