Preheat oven to 350 degrees F (180 degrees C). Line two 9-inch cake pans with parchment paper and set aside.
In a jug, combine Whole Milk (1 cup), Egg (4), and Vanilla Extract (2 1/4 teaspoon) and whisk with a fork until combined. Set aside.
In the bowl of a stand mixer fitted with the paddle, add the Cake Flour (3 cup), Caster Sugar (1 1/2 cup), Baking Powder (4 teaspoon) and Salt (1/2 teaspoon), and give it a quick mix to mix them all together.
Add in the Butter (1 cup) and mix on low until a crumbly mixture forms.
Add in milk mixture and mix on medium low until just combined. Stir in the Sprinkles (1/3 cup).
Divide the cake batter into the two cake pans. Bake them for 30-35 minutes or until a toothpick inserted in the middle comes out clean.
Allow your cakes to cool completely before frosting and decorating as you wish.