If you make your own pumpkin puree, make sure you discard the excess liquid by straining through cheese cloth or a strainer, if it seems watery after roasting or steaming. Then puree until smooth. This affects the consistency of your cookies later
Prepare the cookie dough:
It is important that the egg and butter are at room temperature. The butter should be soft but not melty
Combine all-purpose flour, pumpkin pie spice, salt, and baking powder and set aside
Use a mixer to cream the butter and sugar until pale and creamy over high speed, about 2 minutes. Add egg and continue beating for another minute. Add pumpkin puree and beat for another 20 seconds. Don't overbeat it. We don't need to introduce too much air for these cookies
Fold in the flour mixture and use a sturdy spatula to mix until just combined. Don't overwork it. As long as you don't see any more pockets of flour, you are done mixing. This is very sticky cookie dough. Cover with plastic wrap and chill in the fridge for 4 hours or in the freezer for 2 hours. Please don't skip this step. It's easier for you to work with the cookie dough when it's properly chilled
Shaping:
Preheat oven at 350 F (180 C) for a conventional oven. You may want to lower the temperature by 20 degrees if you use a convection oven. When the oven is done preheating, scoop about 1 1/2 Tbsp (about 30 grams/scoop # 40) of the cookie dough out. With your lightly oiled palms, roll the dough into a round dough ball. The cookie dough is still sticky but easier to work with because it's cold. Place it on a lined cookie sheet, about 2 1/2-3 inches apart
Cover each one in granulated sugar first and then generously roll them in icing sugar. This step prevents the icing sugar from being absorbed by the dough and you won't get the crinkle effect. Roll them about 2-3 times in the icing sugar to make sure each ball is well-coated or the confectioners' sugar will not show much after baking
Pop them into the oven, 3rd rack from the top. Let them bake for 12 minutes for really soft cookies or 13 minutes if you want them crispier on the outside. The edge will set but the center is still soft when you pull them out from the oven. You don't want to overbake if you want a soft and chewy texture. Overbaking these cookies will give you a cakey texture. Let them cool on the baking sheet for 10 minutes then transfer to a cooling rack.