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 vegetable oil, dark brown sugar, canned pumpkin, eggs, and vanilla. Add half of the flour, and mix until just combined. Repeat with the remaining flour.
Spoon two-tablespoon mounds two inches apart on the baking pans. You should have about 36 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 (after they cool for a few minutes at room-temp, I put them in the freezer to speed up the process). Using a piping bag, pipe the Masala chai buttercream (recipe below) onto the flat side of half of the cookies. Place the other half of the cookies on top of the frosted ones, sandwiching them together. Store in a tupperware at room temperature, or freeze for up to two months.