Set the oven to gas mark 180c or 160c if you are using a fan oven.
Grease two 8 inch cake tins and set aside.
Place the flour, salt and baking soda in a separate bowl.
Put the cocoa in a second bowl and add the milk little by little to make a stiff paste.
For the cake batter, in a third bowl, beat the eggs, coconut sugar, vanilla, melted coconut oil, and apple cider vinegar.
Add the flour mixture and the cocoa paste to the wet cake batter and mix until you have a smooth batter.
Pour the mixture equally into the greased tins and place in the oven for 20 to 25 minutes. The cakes are done when a skewer inserted comes out clean. Once cooked, take out of the tins and place on a cooling rack.