Step-by-Step Instructions

• Preheat your oven to 350°F (175°C) and prepare a 15x10 inch jelly roll pan lined with parchment paper.
• Sift together flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large bowl.
• In a separate bowl, beat together eggs, vegetable oil, vanilla, and buttermilk until smooth.
• Gradually combine the wet and dry mixtures, stirring gently until just combined.
• Pour the batter into the prepared pan, spreading it evenly to the corners.
• Bake for 12-15 minutes, checking with a toothpick for doneness.
• Prepare a damp kitchen towel sprinkled with powdered sugar on the countertop.
• Once baked, let the cake cool for 5 minutes, then invert onto the prepared towel.
• Roll the cake tightly in the towel and leave it to cool completely.
• Beat the heavy cream until soft peaks form, then add powdered sugar and vanilla until stiff peaks develop.
• Unroll the cake and spread the frosting evenly over the top.
• Roll the cake back up without the towel and place seam side down on a platter.
• Mix cocoa powder and remaining powdered sugar; dust over the cake.
• Decorate with chocolate shavings or sprinkles.
• Chill in the refrigerator for at least an hour before serving.