Adjust the oven rack to the middle position and pre-heat the oven to 320ºF (160ºC). Grease two 6-inch/15cm round cake tins with vegan butter and line their bottoms with rounds of parchment/baking paper.

In a heat-proof bowl, either in the microwave or over a pot of simmering water on the stovetop, melt the chocolate and oil together.

Add the hot water, non-dairy milk, vegan yoghurt and vanilla to the chocolate-oil mixture, and whisk well until combined. Set aside until needed.

In a large bowl, sift together the gluten free flour blend, sugar, cocoa powder, xanthan gum, baking powder, baking soda and salt.

Add the wet ingredients to the dry, and whisk well (with a large balloon whisk) until you get a smooth cake batter with no flour clumps. The batter will be fairly runny.

Divide the batter evenly between the two prepared cake tins and smooth it out into even layers.

Bake at 320ºF (160ºC) for about 30 minutes or until well risen and an inserted toothpick comes out clean or with a few moist crumbs attached.

Allow the sponges to cool in the cake tins for about 15 minutes, then carefully transfer them out of the tins and onto a wire rack to cool completely. Make sure that the sponges are 100% cooled to room temperature before you level them and start assembling the cake.

Using a hand mixer fitted with the double beaters or a stand mixer fitted with the paddle attachment, cream the butter and powdered/icing sugar until pale and fluffy, for about 5 minutes.

Sift in the cocoa powder and salt, and whip for a further 2-3 minutes, scraping the sides and bottom of the bowl occasionally, until fully combined.Tip: You can tailor the amount of salt to your personal preference – add it slowly (pinch by pinch), mixing well after each addition, and taste before adding more.

Add the melted and cooled chocolate, and whip until fully combined.

If the sponges are domed, level them using a sharp, serrated knife.

Place the bottom sponge on a cake stand or serving plate of choice.

Spread a generous layer of buttercream on top, but leave enough buttercream for the top and sides of the cake. Smooth it out into an even layer, using a small offset spatula.

Place the other sponge on top, with the bottom of the sponge facing upwards (this will give you a nice flat top).

Use the remaining buttercream to cover the top and sides of the cake. Decorate the cake by creating swirls of buttercream – you can do this with a small offset spatula or with the back of a spoon.

Slice and serve.

The gluten free vegan chocolate cake keeps well in a closed air-tight container or wrapped in plastic wrap/cling film in the fridge for 3-4 days.Before serving, take the cake out of the fridge and leave it at room temperature for at least 15-20 minutes. The chocolate buttercream frosting will be fairly firm directly out of the fridge, and leaving it at room temperature for a while softens it to its original luscious, velvety texture.