1. Preheat oven to 140C. In a stand mixer, mix on a medium speed with paddle attachment the flour, sugar, eggs, butter, vanilla paste, milk - until smooth.
2. Divide batter evenly between 5 bowls. Add food colouring to each bowl to get desired colour, start with a small amount (1-2 drops), mix and then add more if needed.
3. Into two pre-lined and greased cake 20cm cake tin, evenly spoon out random spoonfuls of the coloured cake mix. Ensuring that there is half / half for each tin. Using a butter knife, swirl the knife through the mix to create a ripple effect.
4. Place cake tins on lowest rack in oven and cook for 45-50mins or until a skewer comes out clean. Remove from oven and allow to cool in pan for 10mins, then flip out onto a cake rack. Allow to cool completely before starting next steps (at this stage make your buttercream - watch the video HERE...)
5. Once cooled completely, trim cake so that tops are flat and even. Place bottom layer on cake stand or serving plate and butter top with buttercream in a thick even layer. Place second cake on top, face down so that the top is smooth and even.
6. Cover cake with remaining buttercream using a palette knife (do this as best you can, as you will see in the video, I am not amazing at this but a the "rustic" look still works and you will be covering with sprinkles.
7. Cover cake top and sides with your favourite coloured sprinkles! Serve and enjoy!