Preheat oven to 350°F. In a small bowl, whisk together the flour, baking powder, baking soda, salt, pumpkin pie spice, and cinnamon. Set aside. Line two cookie sheets with parchment paper.

In a medium bowl, whisk together the neutral oil, dark brown sugar, pumpkin, eggs, and vanilla. Add half of the flour, and mix until just combined. Repeat with the remaining flour.

Using a #40 scoop, spoon two-tablespoon mounds two inches apart on the prepared baking sheets. You should have about 32 cookies total. Bake, checking for doneness at ten minutes, or until the tops spring back when touched. Mine were consistently perfect at eleven minutes.

Let the cookies cool for a few minutes on the sheet pan and then transfer to a rack to cool completely.

While the cookies are baking, heat the milk and loose-leaf tea in a saucepan over medium-low heat until it comes to a simmer. Allow it to gently simmer for about 1 minute and then remove the mixture from the heat. Steep for 5 minutes. Then, strain the tea leaves out of the milk, pressing the leaves with a wooden spoon to release all of the milk. Let it cool completely.

Meanwhile, beat the butter, sugar, ginger, cinnamon, cardamom, cloves, and black pepper until the frosting comes together, about 3 minutes.** Add the milk tea to the frosting. Beat until the frosting is light and fluffy, about 4-5 minutes.

Place half of the cookies bottom-side up on a sheet pan or plate. Using a piping bag, pipe the Masala chai buttercream onto the bottoms of the cookies.*** Place the other half of the cookies on top of the frosted ones, gently sandwiching them together. Enjoy immediately or store the whoopie pies in a single layer in an parchment-lined airtight container for 2-3 days.