Line the cupcake tin with cupcake cases then set it aside. Preheat the oven to 180C/350F whilst preparing the cupcake mixture.
Into a bowl, sift together the flour, cornflour (corn starch), baking powder, bicarbonate of soda (baking soda), salt and spices. Whisk it all together then set this bowl aside.
155 g (1 cup + 2 tbsp) plain (all purpose) flour, 20 g (2 tbsp + 2 tsp) cornflour (corn starch), 0.75 tsp baking powder, 0.25 tsp bicarbonate of soda (baking soda), 0.25 tsp salt, 2.5 tsp cinnamon, 0.25 tsp cloves, 0.5 tsp allspice, 0.5 tsp ginger, 0.75 tsp nutmeg
In a jug, mix together the yogurt and milk.
30 g (2 tbsp) yogurt (I used Greek), 30 ml (2 tbsp) whole milk
In a large mixing bowl, beat together the butter and sugar until fluffy. Add in the egg and vanilla and beat it all together until the mixture is pale and really light and airy.
70 g (¼ cup + 1 tbsp) unsalted butter, at room temperature, 150 g (¾ cup) caster sugar, 1 large egg, 0.5 tsp vanilla
Add the pumpkin pure to the butter mixture and beat on low speed until just combined. If the mixture looks a little curdled, no need to fret, it will all come together in the end.
140 g (½ cup) pumpkin puree
Tip in half the flour mixture into the pumpkin bowl, then mix to combine. Add in all the buttermilk and beat until mixed and smooth, then add the remaining flour mix and beat again until combined. Do not over mix.
Spoon or scoop the cupcake mixture evenly between the 12 cases, then bake in the preheated oven for 18 minutes until springy to touch and a wooden skewer or toothpick inserted into a cupcake comes out clean. Leave them to cool for ten minutes in the tin, then remove the pumpkin spice cupcakes to a cooling rack and allow them to cool completely.