Preheat the oven to 350°F (180°C) or 160°C if using a fan oven. Line 4 baking sheets with parchment and set aside
In a medium mixing bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda, and salt; set aside
In a separate larger bowl, whisk together the pumpkin, sugar, brown sugar, melted butter, eggs, and vanilla until smooth.
Add the dry ingredients to the wet ingredients and whisk until just combined. Use a small ice cream scoop (about 2.5-3 tablespoon scoop) to scoop the batter onto the prepared baking sheet at least 2” apart. Bake the cookies in the preheated oven for 12-15 minutes, or until a toothpick inserted in the center comes out clean and they are no longer wet on top.
Allow the cookies to cool on the baking sheet for 10 minutes before transferring to a wire rack to cool completely
Prepare the filling by creaming the butter and cream cheese until smooth, about 3-4 minutes. Add the powdered sugar and mix until smooth. Beat in the heavy cream and the vanilla extract, then beat on high an additional 2-3 minutes until the filling is light and creamy.
Once the cookies have cooled completely, flip half upside down (flat side up) and pipe or spread a generous amount of filling on top. Add another cookie on top, flat side down, and press down gently to create the cookie sandwich.
Chill the cookies in the fridge for at least 30 minutes to firm up before serving.