Heat your oven to 350°F and line a baking sheet(s) with parchment paper. (We used two half- sheets (16x12 inches) and baked the 40 cookies in two batches.)
In a large bowl, mix together the flour, baking powder, baking soda, cinnamon, pumpkin pie spice, xanthan gum, and salt.
In another large bowl, beat the butter with an electric mixer until it is fluffy, then add the granular erythritol and eggs.
Beat for one minute, then add in the pumpkin puree and vanilla and beat again for another minute.
Slowly, add your dry ingredients into the wet ingredients and beat until well combined.
Take the batter 1 tablespoon at a time and spoon it onto the baking sheets.
Wet your finger with water and smooth out the spoonfuls of batter until they are flat 2-inch diameter circles.
Bake for 12 minutes or until the edges begin to brown.
Let the pumpkin bread cookies cool completely before assembling the whoopie pies.