Preheat your oven to 350°F (175°C) and prepare a baking sheet.
Whip the eggs and granulated sugar until pale and fluffy.
Sift together the flour, cocoa powder, baking powder, and salt.
Gently fold the dry ingredients into the egg mixture.
Spread the batter evenly onto the prepared baking sheet and bake.
While the cake is baking, prepare a clean kitchen towel and dust it with powdered sugar.
Once baked, invert the cake onto the powdered sugar-dusted towel and peel off the parchment.
Roll the cake tightly using the towel and let it cool completely.
To make the peppermint ganache, heat the heavy cream until just simmering.
Pour the hot cream over the chopped dark chocolate and let it sit.
Stir in the peppermint extract until fully combined.
Unroll the cooled cake and spread a layer of ganache on top.
Roll the cake back up without the towel and chill for at least an hour.
Dust the Swiss roll with powdered sugar before serving.
