For the cake, melt the buttered mix in the caster sugar. Add the eggs and mix through, then the flour and vanilla until incorporated. Divide equally into 2 6 inch cake tins and bake at 180°C for 30-40 minutes until they are cooked through.
For the buttercream, beat together the icing sugar, butter and milk and add the seeds from the vanilla pod. Keep beating until the mixture is light and fluffy.
Cut each cake into 2 layers so you have a total of 4 layers of cake.
Put first layer onto a cake board or plate with a little buttercream underneath so it doesn't slip.
Pipe or spread some buttercream onto the layer of cake and sandwich another on top.
Repeat until you get to the last layer of cake, turn the layer upside down to ensure the top is the flat part from the cake tin.
Smother buttercream over the whole layered cake and scrape away the excess (crumb coating).
Refrigerate or freeze for 20 minutes until the buttercream has hardened.
In a separate bowl, mix a couple of heaped tablespoons with some food colouring to get a dark colour.
Spread a thin layer of the coloured buttercream around the bottom of the cake.
Add some more white buttercream to the coloured one to make a lighter shade, and spread it on the cake just above the layer you just did.
Repeat until you get tho the top where you want to spread white on the top layer and the top of the cake.
Use a scraper or palate knife to go around the cake and smooth out the sides and you should achieve the ombre effect.
- Even out the top of the cake so its flat and decorate however you would like!