Pumpkin Snickerdoodle Whoopie Pies
(makes about 3 dozen cookies / 18 whoopie pies)
1. Make the cookies:
In a mixing bowl, beat the butter and 1 cup sugar on medium speed for about 5 minutes. Add the egg and vanilla and beat for 1 minute. Add the pumpkin and beat until well combined.
In a separate bowl, whisk together the flour, 1 teaspoon cinnamon, salt, baking soda, baking powder and cream of tartar. Turn the mixer to low speed and add the dry ingredients by spoonfuls to the batter. Mix just until combined.
Cover the mixing bowl with plastic wrap and refrigerate dough for two hours.
Preheat the oven to 350 F. In a small bowl, combine 3 tablespoons granulated sugar with 1 1/2 tablespoons cinnamon. Form the dough into 1 1/2 inch balls and roll in the cinnamon/sugar mixture. Place the balls 2 inches apart on a cookie sheet lined with a Silpat baking mat or parchment paper. Bake for 12 minutes.
Slide the Silpat or parchment paper off the cookie sheet and cool cookies completely.
2. Make the cream filling.
Using the whisk attachment on your mixer, beat the egg white for 2 minutes until foamy. Add the milk and vanilla and beat for another 2 minutes. Add 1 cup of powdered sugar and the butter and beat for several minutes to combine. Add the remaining cup of powdered sugar and beat for 8-10 minutes until cream filling is very light and fluffy.Spoon dollops of the filling onto the underside of half the cooled cookies and top with another cookie. Refrigerate any leftovers.