With a stand mixer fitted with a paddle or an electric hand mixer, combine butter and sugars until light and fluffy.
Add egg and pumpkin and mix until well blended.
Sift flour, baking powder, cinnamon, ginger, nutmeg, and salt over the wet mixture.
Mix until just combined, then place the snickerdoodle dough into the fridge for at least one hour.
When you're ready to bake, preheat your oven to 350°F, 180°C. Line a baking sheet with parchment paper.
In a small bowl combine brown sugar, cinnamon, and ginger.
Scoop out about 2 Tbsps of chilled snickerdoodle dough and roll in a ball in the palms of your hands.
Toss with cinnamon sugar, and place on the prepared baking sheet. Repeat until sheet is full, giving cookies some space for spreading.
Take a smooth bottomed glass and dip the bottom in water and then in the cinnamon sugar. Press onto the cookies to slightly flatten. If the glass starts to stick to the cookies, re-coat the bottom in sugar.
Bake for about 15 minutes, rotating pan half way through baking. Transfer to a wire rack to cool cookies. Enjoy!