Preheat the oven to 160°C fan / 180°C conventional. Grease and line the base and sides of two 8-inch round cake tins with baking paper. In a large mixing bowl, whisk together all the wet ingredients (apart from the boiling water) until fully combined. Set aside.
200 millilitre Vegetable or sunflower oil, 150 millilitre Buttermilk, 4 medium Eggs
In a separate bowl, whisk together all the dry ingredients until thoroughly combined. Make sure there are no lumps hiding in the mix. Give it a proper stir, scooping right down to the bottom of the bowl to ensure everything’s evenly blended.
200 grams White caster sugar, 350 grams Self-raising flour, 70 grams Menier 100% cocoa powder, 1 teaspoon Espresso powder, 1 teaspoon Bicarbonate of soda
Add the dry ingredients to the wet in two stages, gently whisking after each addition until the batter almost comes together. Pour in the boiling water and whisk slowly until you have a smooth, glossy chocolate mixture. The batter should be runny and thin.
150 millilitre Boiling water
Divide the mixture evenly between the tins (using weighing scales helps with accuracy) and bake for 30–35 minutes, or until the sponges are well risen and spring back when lightly pressed in the centre. Leave the cakes to cool completely in the tins. Then carefully turn out upside down onto a wire rack and peel off the greaseproof paper.