Preheat a fan-forced oven to 160C (320F) or 180C (356F) for a conventional oven. Line a cupcake tin with cupcake liners.
In the bowl of a stand mixer fitted with the paddle attachment, add the flour, baking powder, caster sugar and salt. Turn mixer on low speed and allow it to mix for a couple minutes to help everything combine well (alternatively you may do this by sifting the ingredients together). Add the softened butter and let it mix until it resembles a fine sand like texture.
Next, add milk, eggs, yogurt, oil and vanilla extract in a large jug and whisk well.
Add wet ingredients to dry ingredients in a slow and steady stream until no dry ingredients are visible. Scrape down the bowl and mix for another 20 seconds.
Split the batter between three bowls. Colour one blue, one pink and the other with 2 drops of pink and two drops of purple. Transfer batter to three separate piping bags and pipe little blobs of each colour in the cupcake liners until it’s filled ¾ of the way.
Bake for 20-25 min or until a toothpick inserted comes out clean. Allow them to cool completely on a wire cooling rack before frosting.
To prepare frosting colour each one blue, purple and pink (same as the batter). Fit the end of a piping bag with a round tip and add a teaspoon of each coloured frosting in the bag (just randomly)
Core the centre of each cupcake and fill with sprinkles.
Frost three blobs of frosting on the cupcake. The bottom one being the biggest and the top one being smaller. Continue piping little blobs around each blob finishing with one final blob on top.
Cupcakes can be stored in an airtight container for up to three days.