Preheat your oven to 180°C fan / 200°C. Lightly grease your Swiss roll tin and line with non-stick baking paper.

Separate your eggs into two small bowls - egg whites in one and yolks in the other.

In a large mixing bowl, add your egg yolks and half the caster sugar (50g). Whisk together until combined, then add your vanilla, milk and oil and whisk once more. Sift in the flour, cocoa powder and xanthan gum, and mix in until well combined, thick and glossy.

In a separate bowl, whisk your egg whites (using an electric hand whisk or stand mixer ideally) until they start to turn white and frothy. Gradually add the remaining caster sugar (50g), whisking until you have medium peaks.

In three stages, add your egg white mixture to your egg yolk mixture, folding it in carefully between each addition using a silicone spatula. Once all the egg white mixture is fully folded in, pour your mixture into your prepared tin. Spread it out gently to make sure it’s nice and even and bake in the oven for 10–12 minutes until cooked through.

Place a piece of non-stick baking paper on your work surface and dust it with the icing sugar.

While your sponge is still warm, loosen it from the tin and flip it out onto the baking paper. Peel off the baking paper on top that once lined the tin – don’t worry if you lose the outer layer of the cake because it sticks to the paper as you peel it off, that’s totally normal. Using your baking paper, roll the sponge up from the short end – the paper should be inside it as you roll. Try to roll fairly tightly, then leave the sponge to cool fully while rolled up. I prop something up against it to stop it from unrolling itself.

While the sponge is cooling you can prepare the filling. Melt your chocolate (I do this is the microwave in short bursts, mixing in between) then put to one side to cool whilst making the rest of the icing.

Place your softened butter in the bowl of a stand mixer (or a large mixing bowl if you intend to use an electric hand whisk), mix on its own on a high speed for about 5 minutes. The butter should change from a more yellow colour to being a lot more pale.

Add your icing sugar gradually to the butter (I do this in two stages). I mix each addition of icing sugar for around 3-5 minutes before adding the second half. Now add in your melted, cooled chocolate and mix until fully combined. It should be the right consistency at this point.

Carefully unroll your sponge and remove the baking paper. Fortunately I never find the sponge cracks using my recipe, but if it does a little, it doesn't matter - it will all be covered in icing - just be delicate!

Spread a layer of about 1cm thick of your filling on the unrolled sponge (I leave about a half cm gap around the edge). Carefully roll the sponge back up and transfer it to a serving board or plate. Do this as tight as you can for the best swirl.

Cover the rolled up sponge with the rest of the icing. As I said, you don't have to use it all. It can be kept in the fridge for other baking!

Cover in mini eggs, crushed and whole. Cut the ends of to reveal your swirl and enjoy!