Prepare your tins. Grease and line 2 round cake tins with parchment paper.
Preheat the oven to 180C (160C Fan)
If making your own buttermilk, add 1 tbsp lemon juice to a jug and then add 240ml of milk. You can use dairy or non dairy milk. Stir thoroughly and then allow to sit for 5-10 minutes. The 'buttermilk' will then be ready to use.
Sift all your dry ingredients into a bowl (flour, cocoa powder, baking powder, bicarbonate of soda and sugar).
In a separate large bowl mix together the vegetable oil, buttermilk, eggs and vanilla extract until thoroughly combined. (I used an electric hand mixer)
Gradually add your dry ingredients to your wet ingredients. You can do this by hand or with your electric mixer on very low.
Add your hot coffee or hot water and mix. I just used my electric hand mixer on very low. (Don’t worry at how thin the mixture is. It will cook in the oven to make a super moist cake!)
Carefully pour your cake mix into your tins evenly and place in the oven for around 25-30 minutes. (Check with a skewer to make sure it is cooked through - it will be very soft whilst warm!)
Leave to completely cool.
For the icing. Beat your butter until pale and creamy, I did this for around 3-5 minutes.
Sieve your icing sugar and cocoa powder. Add in your icing sugar and cocoa powder in 2-3 additions. Start the mixer slowly and then go to a medium/high speed for about 3 minutes between each addition.
If adding your cream/milk add it in and mix for a further minute.
At this stage your icing should be done and taste great. However, again if you prefer a thicker icing then the best idea is to add more icing sugar. (I don’t think its necessary, however with dairy free you often do need a little extra)
Place one of the cake tiers on a serving place and spread the icing on top. Then place the other cake tier on top like a sandwich.
Spread the icing on the top and round the sides of the cake using a spatula.
It’s ready to serve up! (You can allow it to set for a short while. You could even put it very briefly in the fridge to chill - but again probably not necessary) Enjoy!