Preheat your oven to 170C.
Prepare 2 swiss roll tins - grease them and line the bottom with NON-STICK baking paper (my tins were 32cmx23cm so something around this size would be ideal).
Sieve your cocoa powder into a bowl (it's always important to sieve this to avoid lumps) and add your melted spread, vanilla extract and boiling water to the bowl. Mix together - it will form a stiff paste.
Separate all your eggs and place the yolks and whites in separate bowls.
Whisk together your egg yolks and 100g of caster sugar until thicker but nice and light. Then add your chocolate mix and whisk more until combined.
In another bowl whisk your egg whites together to form stiff peaks, then add in your 50g of caster sugar and continue to whisk until combined.
Whisk in about a third of the egg white mixture into the chocolate mix and then carefully fold in the rest, keeping it light and airy.
Spoon the mixture into your two tins and place in the oven for about 12 minutes. (I popped mine on the middle shelf and did them one after the other as my oven couldn't fit them both on the middle shelf)
Once cooked, remove from the oven and leave to cool completely in the tin on cooling racks.
You have the choice of making two types of buttercream filling - chocolate or vanilla. For the vanilla, cream the butter and then gradually mix in the icing sugar and vanilla extract. For the chocolate icing, cream the butter, mix in the icing sugar, vanilla extract and cocoa powder. (For me it's ESSENTIAL to pop these in the fridge or freezer briefly when dairy free to help solidify first - they can be too runny otherwise)
Take your now cooled sponges and turn them upside-down onto baking paper on a flat surface. Start by peeling off the baking paper stuck to the back of the sponge.
With the shortest side facing you, score a 4cm line across the width of the sponge. This will help it roll easier in a minute. Do the same at the other end too.
Spread your buttercream filling (chocolate or vanilla) over the sponge evenly until it's about equal thickness to your sponge.
Ready to roll? We're going to make two rolls out of each sponge. Start with the shortest side facing you and just roll it up until halfway. Then leave that there for a mo and do the same with the opposite shortest side too. They should meet in the middle, where you can then cut and separate them into two long mini rolls.
Repeat this for your other sponge so you end up with 4 long mini rolls. You should then be able to cut them into thirds and end up with 12 mini rolls ready to be coated in chocolate.
Place the mini rolls in the fridge, seam side down until you are ready to cover them in chocolate. (I leave mine for about 20 minutes minimum)
Melt your dark/milk chocolate and drizzle/spoon it over the top of each of your mini rolls, aiming to completely cover them. I found the chocolate being really hot helped. I also had my mini rolls on a cooling rack with baking paper beneath to catch the excess chocolate. Once done, return to the fridge to allow the chocolate to completely set hard.
Finally, melt your white chocolate and either drizzle lines or use a piping bag to pipe lines of white chocolate across each mini roll. Allow to briefly set and then enjoy!