• Preheat the oven to 170oc (fan).
• Line at 23 x 33cm swiss roll tin with baking paper.

  >You can use a baking tray of different size, just make sure its deep enough so that the sponge can rise to at least 2/3cm
• Whisk together the eggs and sugar for 5 mins, until light and fluffy and very thick.

  >This is realllyyyy important – set a timer! It should expand by about 3-4x, like my picture.
  
• Sift in the flour and cocoa powder and whisk again for 20 seconds until combined. Make sure you whisk right to the bottom as the flour all sinks there. Pour into the baking tray.

  >Don't overwhisk at this stage as you'll lose all that lovely air you've whipped into the egg/sugar. If you're nervous, FOLD the flour/cocoa powder in rather than using the whisk.
• Bake the sponge for 10-12 mins or until firm to touch and starting to brown.
• Whilst that’s baking, prepare the following: place a sheet of baking paper (a bit bigger than the size of the baking tin) onto your work surface. Place something on the corners to hold it down if it keeps rolling up! Scatter the baking sheet with icing sugar (be generous!).
• Once the sponge is cooked, remove from the oven and turn the sponge out onto the sugared baking paper. The key is to be confident with it!
• Carefully peel off the baking paper you’ve cooked the sponge in and begin to roll, leaving the fresh, sugared paper attached to the cake (i.e. the paper rolls up with the cake!)

  >I like to roll from the short edge, hopefully you can see in this pic where I've started to roll it.
  
• Leave it rolled up to cool COMPLETELY (takes at least 30mins, depending on where it is).
  

Buttercream

• Add the butter and icing sugar to a bowl and whisk for at least 3 mins, until the buttercream is light and fluffy.
• In a seperate bowl, crush all of the oreos (doesn't have to be a smooth consistency, I like to have a few bigger oreo pieces in there.
• Add the oreos to the buttercream and mix everything together.

  >You can use a whisk for this, or just use a spoon and mix it all together.

Construction

• Once cool, unroll and spread with a thick layer of buttercream.
  
• Roll the swiss roll back up, as tightly as possible to get the best cake swirl shape! Make sure the join is sitting on the worktop/plate to prevent the swiss roll from unrolling

Ganache Topping

• Add the cream to a pan and bring to the boil.
• Whilst it starts to boil, break the chocolate up into square and place into a large bowl.
• Pour the boiling cream over the chocolate and leave for 2-3mins.
• Whisk the mixture together to form a smooth, delicious ganache!
  
• Wait a couple of minutes for it to thicken slightly and then pour the ganache over the swiss roll.

  >Tip: Place the swiss roll on a cooling rack, ontop of a baking tray. The excess ganache will just fall through the cooling rack and onto the baking tray, making a neater swiss roll and to help with the cleaning up!