Soft, fluffy pumpkin whoopie pies with vanilla buttercream filling.
Combine the brown sugar and oil. Add the pumpkin, eggs, and vanilla, then stir.
Sift together the flour, salt, baking powder, baking soda, and spices. Add to the wet ingredients and stir.
Using a piping bag, pipe mounds of batter onto a lined sheet tray. Bake and let cool.
Make the filling. Spread it on one cookie and top with another.