Preheat the oven to 180°C (350°F) and line a 12-cup muffin tin with paper liners, and another with 2 liners.
In a large bowl, whisk together the plain flour, baking powder, bicarbonate of soda, pumpkin pie spice, and salt.
In a separate bowl, mix together the canola oil, white sugar, pumpkin puree, vanilla extract, and dairy-free milk until smooth and well combined.
Gradually add the wet mixture into the dry ingredients, mixing until just combined. Be careful not to overmix the batter.
Divide the batter evenly among the 14 muffin liners, filling each about ¾ full.
Bake for 18-22 minutes, or until a toothpick inserted into the centre of a cupcake comes out clean. Allow the cupcakes to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.
Once completely cool, frost the cupcakes with vegan cream cheese frosting or vegan vanilla buttercream. If desired, sprinkle chopped pecans on top of the frosting for extra texture and flavour.