Preheat your oven to 350°F (175°C) and line a 15x10 inch jelly roll pan with parchment paper, allowing some overhang for easy removal.

In a large mixing bowl, sift together the flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt. Use a whisk to mix the dry ingredients thoroughly for about 1–2 minutes until fully combined.

In a separate bowl, beat together the eggs, vegetable oil, vanilla extract, and buttermilk until smooth.

Gradually pour the wet ingredients into the dry mixture, using a spatula to gently mix until just combined.

Pour the batter into the prepared jelly roll pan, spreading it evenly into the corners using a spatula.

Place the pan in the preheated oven and bake for 12-15 minutes. The cake is done when a toothpick inserted in the center comes out clean.

While the cake is baking, prepare a clean kitchen towel and sprinkle powdered sugar generously over it.

Once the cake is done, remove it from the oven and let it cool for 5 minutes. Invert the warm cake onto the prepared towel.

Roll the cake up tightly starting from one short end, with the towel included, and let it cool completely in this rolled-up shape.

In a medium bowl, beat the heavy whipping cream until soft peaks form. Gradually add the powdered sugar and vanilla extract.

Once the cake has cooled completely, carefully unroll it from the towel. Spread an even layer of the whipped cream frosting over the cake.

Roll the cake back up without the towel, rolling tightly but gently to preserve the structure.

In a small bowl, mix together the cocoa powder and remaining powdered sugar for dusting. Lightly sprinkle or sift this mixture over the top of the cake.

Chill the finished Yule Log in the refrigerator for at least an hour before slicing.