Preheat oven to 350F and line 2 baking sheets with parchment paper. 

Combine flour, salt, baking soda, baking powder, and pumpkin pie spice in a mixing bowl and set aside.

In a separate bowl, whisk together sugars and oil until well combined. Whisk in the eggs until fully incorporated and smooth. Whisk in the pumpkin puree.

Fold dry ingredients into wet and mix until the batter is smooth and no clumps remain.

Add batter to either a large piping bag or plastic bag. Cut a small tip off the corner.

Pipe the batter out into roughly 2 inch sized discs spaced 2 inches apart on parchment lined baking sheets. You should be able to make 32 discs.

Wet a clean finger and smooth out the tops rewetting as necessary so the batter doesn't stick to your finger

Bake in the oven for 13-15 minutes. They should deepen slightly in color. Allow to cool fully.

Make the frosting by beating the butter and cream cheese together with an electric mixer. Beat powdered sugar and vanilla extract in. Continue beating on hight for 3 minutes until a smooth and fluffy frosting remains

Pipe the frosting onto half of the disks and top with the other half. 

Allow the whoopie pies to rest for 30-45 minutes in a cool place for the icing to set up then enjoy!