Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line two 8" cake tins (that are at least 2" deep)
In a mixing bowl, or a large jug, whisk together the vegetable oil, dairy free milk, vanilla extract and cider vinegar
In another mixing bowl, stir together the caster sugar, self raising flour and baking powder
Make a well in the centre of the flour mixture, and pour in the oil and milk mixture, whisk them together gently with a hand whisk until smooth, be careful not to over mix
Divide the mixture between the tins, use scales for accuracy if you like
Bake them for 35-40 minutes or until they are risen and a skewer inserted in the centre comes out clean. Leave them to fully cool either in the tins or remove from the tin and place on cooling racks
Make the buttercream by first mixing the dairy free butter on it's own for a few minutes until creamy. Then add the icing sugar, dairy free milk and vanilla extract, and mix until smooth. You can do this by hand or for best results use an electric mixer. If the buttercream is too stift, you can add more dairy free milk
If the cakes have domed on top, you can level them off with a cake leveller or a serrated knife
Put one of the sponges on your plate or cake stand and pipe or spread some of the buttercream onto it. Then top with the jam, I just spooned it on
Add the second cake layer, then dust the top with icing sugar
Store leftovers in an airtight container in a cool place and eat within 3 days