- Preheat the oven to 180°C and line a muffin tin with cupcake cases. 
- In a bowl, cream together softened butter and sugar until light and fluffy. Add an egg and vanilla extract, then gradually incorporate the flour and baking powder. Finally, mix in the milk. 
- Spoon the batter into the prepared muffin tin, filling each cup about halfway. Bake for 12-15 minutes or until a toothpick inserted into the center comes out clean. Allow the cupcakes to cool completely. 
- For the icing, beat the softened butter until creamy and fluffy. Slowly add powdered sugar, and if needed, incorporate a splash of milk to achieve the desired consistency. Divide the icing into three bowls and add a drop of food coloring to each bowl. Transfer each colored icing into a piping bag with a star nozzle. 
- Once the cupcakes are cooled, pipe the colored icing onto each cupcake in a swirl pattern. Finish by sprinkling with your favorite sprinkles.