Preheat the oven to 180 degrees Centigrade/Gas Mark 5. Grease and line 2 20cm sandwich tins
Sift together the flour, custard powder, bicarb and salt
Stir in the sugars
In a separate bowl, mix together the dairy-free milk, melted dairy-free margarine, yogurt and caramel flavour.
Mix the wet ingredients into the dry. Mix gently until well combined.
Pour into the cake tins and bake for 30 minutes, until a knife comes out clean
Cool on a wire rack
Meanwhile, whisk together the dairy-free butter and icing sugar, using more sugar if the buttercream is too wet. Whisk in the vanilla
Sandwich the cakes together with the buttercream and generously dust the top of the cake with icing sugar