Preheat the oven to 160°C/320°F. Line 3 x 15-17.5cm (6-7") cake pans.
Place all the ingredients into a bowl; mix until smooth and combined.
Divide the batter into 3 equal portions. Flavour each per the recipe or as preferred.
Pour the batters into the prepared cake pans. Place the pans on the shelf in the centre of the oven. Bake, 20-25 minutes or until a skewer comes out clean. Leave to cool in the pan for 15 minutes before turning out to cool completely. Chill for at least 3 hours before frosting.
Divide the batter into 3 bowls. I used half of the batter as one colour (white) to include the layering between the cakes and the remaining half was halved.
Place the first cake onto a cake turntable or plate. Pipe a circle of the darkest frosting on the outer edge. If you have more of the lighter colour frosting then pipe that into the centre. Smooth over the top with an angled spatula. Don't worry if it comes over the edge as you need the frosting to coat the outside too.
Add the next cake layer and pipe some of your next coloured layer around the outside of the cake surface(working from darkest colour up to light this would be your next lightest colour). Pipe some of the white frosting into the centre. Top with the final layer of the cake.
Pipe the top layer with the remaining white frosting.
Starting from the outer edge of the bottom of the cake. Pipe around the outer edge of the bottom layer with the remaining darkest colour frosting. Pipe the centre with the mid-level colour and do the top with light colour frosting. Using a cake scraper, angled spatula (or even a ruler - in a pinch) gently scrape and smooth the sides of the cake. Remove the excess frosting and place it into a bowl. Clean the spatula or smoothing scraper before starting again. Do this until the edges of the cake are smooth. If you have any holes or unevenness just add more of the frosting previously removed. Add any garnishes of preference and chill for a few hours before serving.