Preheat & Prep – Preheat your oven to 180°C (350°F) and line a muffin tin with cupcake cases.
Make the Batter – In a mixing bowl, beat the softened butter and sugar together until light and fluffy. This step is crucial because it gives your cupcakes that tender texture. Add in the egg and vanilla extract, mixing until everything is well combined.
Add the Dry Ingredients – Slowly mix in the flour and baking powder. You don’t need to overdo it, just stir until no flour streaks remain. Finally, add the milk and mix until the batter is smooth.
Bake – Spoon the batter into the prepared cupcake liners, filling each about halfway. Pop them in the oven and bake for 12-15 minutes, or until a toothpick inserted in the center comes out clean. Let them cool completely before decorating (I know, waiting is hard!).
Make the Icing – In another bowl, beat the softened butter until it’s light and fluffy. Gradually add in the powdered sugar, mixing until smooth. If needed, add a splash of milk to adjust the consistency.
Add Color & Decorate – Divide the icing into three bowls and add a drop of food coloring to each, stirring well. Transfer each color into a piping bag fitted with a star nozzle. Swirl the icing onto each cupcake and finish with a generous sprinkle of your favorite sprinkles.