Melt the butter and allow to cool.
In a bowl or stand mixer, add the butter and sugar and work for a minute or two.
Add the egg and vanilla extract, and continue to work for a further minute and finally, add the milk and give it a quick whizz just to ensure everything is evenly combined.
Add the flour, baking powder, and baking soda, and on the lowest speed, work until evenly combined.
Pour into ten cupcake or muffin holes almost to the very top.
Sprinkle over the topping and bake for around 15-17 minutes (depending on how large your muffin cases are).
Remove from the oven, allow to cool for a while, then enjoy while still warm!