Preheat the oven to 350 degrees. Line your cupcake pans with white cupcake wrappers.
Place your self-rising flour, cake flour, and sugar in the bowl of your mixer.
Mix them together for a minute or two until they are well combined.
Cut your butter into tablespoon pieces.
Slowly add your butter into the flour mixture one piece at a time continue mixing until you have reached the texture of sand.
Pour half of your milk into the flour mixture and mix just until the milk is incorporated. Use your rubber spatula to scrape down the sides of your bowl. Add your remaining milk and the vanilla to your batter and mix until combined.
Slowly add in one egg at a time to the cake batter, making sure each egg is incorporated before adding the next egg.
Divide the batter into three separate bowls. Color one bowl purple, one bowl green, and one bowl yellow.
Scoop the batter into the prepared cupcake pan, filling them 1/4 of the way full with the green batter. Then top them with the purple batter filling them another 1/4 full. Finally, top them another 1/4 with the yellow batter.
Bake for 10 minutes then rotate the cake pans so the pan that was on the top rack is now on the bottom and the pan that was on the bottom is now on the top rack. Continue to bake for another 10-13 minute until a toothpick comes out clean from the center of the cupcake.
Transfer the cupcakes to a cooling rack until they have reached room temperature.