Start by preparing three 8-inch pan, by buttering on all sides, dusting it with flour and tap off the excess flour. Set this aside.
Preheat oven to 180 degree C.
Take cocoa, food colouring powder, ¼ cup of buttermilk and mix to a paste. Set aside.
Now take butter, oil, sugar, vanilla in a large bowl, Use a electric beater to cream this up.
Now add in eggs and cream again.
Add in cocoa food colour mix and mix well.
Add in flour, salt, buttermilk and fold gently.
Now take baking soda in a bowl, add in vinegar. It will bubble up. pour this into the batter and mix gently. This will lighten the batter.
Divide this between the cake pan and bake for 25 to 30 mins.
Remove it and let it cool comepletely
Meanwhile prepare your frosting, check this link for all frosting recipe in this blog.
Spread frosting between each layer of cake, sandwich the cakes, spread frosting all around the sides and serve.