Preheat oven to 190°C/170C Fan/Gas 5. Line a 12 hole muffin tin with paper cases.
Sift the dry ingredients for the cupcakes into a large bowl and mix together.
Using a stand mixer of electric hand mixer, cream the butter and two sugars together until fluffy.
Add the egg and mix until well combined. Add a spoonful of the flour mixture if it looks like it's about to curdle.
Stir in the milk and pumpkin puree using a spatula or spoon.
Fold in the dry ingredients until fully combined but not overly mixed.
Spoon the mixture evenly between the 12 paper cases and bake in the oven for 15-25 minutes until they are golden brown or a toothpick comes out clean.
Leave to cool while making the icing.