For the buttercream, you will want to use a fresh black tea to make sure the tea flavor comes through. I like to use Assam, but any strong black tea will do. The pumpkin cookies themselves are not super sweet to make up for the sweetness of the buttercream. If you like your desserts a little sweeter, add up to 1/4 cup of more sugar to the recipe.
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.
While the cookies are baking, heat the milk until slightly hot over the stove or in the microwave. Add the black tea, and let it steep for at least five minutes. Set aside to cool.
Meanwhile, beat the butter and sugar until whipped, about three minutes. Add the ginger, cinnamon, cardamom, cloves, and black pepper until combined. Strain the tea out of the milk, discarding the tea leaves. Add the milk-tea to the frosting, beating until combined and fluffy. If the buttercream is too runny, add more powdered sugar two tablespoons at a time, until it is your desired consistency.