Start by melting the butter slowly in a saucepan over low heat, allowing it to brown slightly and develop a nutty aroma, then transfer it to a mixing bowl to cool slightly.
Add the brown sugar to the browned butter and whisk until smooth and well combined.
Stir in the pumpkin puree and a large egg, mixing until the mixture is thick, smooth, and fragrant.
In a separate bowl, sift together the flour, cinnamon, ginger, allspice, the secret spice, baking powder, and salt.
Gradually fold the dry ingredients into the wet mixture, stirring gently until just combined and a soft, slightly sticky dough forms.
Chill the dough in the refrigerator for about 15 minutes to relax the gluten and make it easier to handle.
Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Using a tablespoon or cookie scoop, portion out the chilled dough and gently shape into balls, placing them onto the prepared baking sheet. Flatten slightly if desired.
Bake for about 12 minutes, or until the edges are golden and the cookies feel set when lightly pressed.
Remove from the oven and let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
Enjoy these cookies once cooled, savoring their soft texture and warm spice aroma, perfect for autumn celebrations or cozy afternoons.