Preheat your oven to 175°C and line a cupcake pan with muffin liners (or cupcake liners).
In a mixing bowl, whisk together self-raising flour, cocoa powder, pumpkin spice powder, baking powder, and salt. Sift and set aside.
In a separate bowl, cream together butter and granulated sugar until light and fluffy. Scrape the sides and bottom of the bowl half way through.
Beat in the eggs, one at a time. Each time, beat until all the traces of the eggs are no longer visible. Scrape the sides and bottom of the bowl half way through (see Note 1).
Next, add the pumpkin puree and beat well. The creamed mixture will appear curdled after adding the pumpkin puree and that is fine.
Gradually add half of the flour mixture (dry ingredients) into the wet ingredients and fold until well combined.
Add the milk and fold again, followed by the remaining flour mixture. Scrape the sides and bottom of the bowl to make sure the ingredients are well folded in.
Finally, add the vanilla extract and mix well.
Pour the batter into the cupcake liners, filling each about two-thirds full (see Note 2).
Bake the cupcakes for 15 minutes or until a toothpick inserted into the center comes out without any wet batter sticking to it. You can also test by pressing the top of the cupcakes. They should spring back when pressed lightly with a finger.
Transfer the cupcakes onto a wire rack. Let them cool to room temperature before decorating.Keep the cupcakes covered with a kitchen towel to prevent them from becoming dry as they cool down.