1. Preheat oven to 400℉. Line 2 large baking sheets with parchment paper and set aside.
2. Prepare flax egg by placing 2 Tbsp. flax meal + 6 Tbsp. water in a small bowl, whisking to combine and allow to rest 8-10 minutes until a gel forms.
3. In a large bowl add flour, sugar, pumpkin pie spice, baking powder, and sea salt. Whisk to combine well.
4. Using a pastry blender or 2 knives, cut the chilled butter into the dry mixture until it resembles coarse crumbs.
5. Add the flax eggs, pumpkin, and vanilla to the dry mixture then stir with a large spoon until the dough forms into a ball (we like to work the dough into a ball with clean hands). The dough should be smooth to the touch (maybe a hair sticky). If the dough is wet and sticky, add a little more flour and stir again. If the dough is dry, add a splash of water and stir again.
6. Roll dough into 28-30 golf-ball-sized pieces, placing on two baking sheets allowing enough room so that they won’t touch when flattened.
7. Using your hand, gently flatten each ball of dough so that it’s about ¼-inch thick and 2 ½-inches in diameter.
8. Place pans in the oven and bake 10-12 minutes or until bottoms are lightly browned and the tops of the cookies are set – rotating the pans back to front (spin ‘em) and top to bottom (swap ‘em) halfway through cooking time.
9. Use a spatula to carefully remove cookies to a wire rack to cool completely before frosting.

To make the frosting:

1. Place softened butter, cream cheese, and vanilla in a medium bowl (or bowl of a stand mixer).
2. Beat until well combined. Add powdered sugar and pumpkin pie spice and continue to beat at high speed until fluffy.
3. Spread frosting on cooled cookies and dust with additional pumpkin pie spice or sprinkles.