Preheat oven to 350 degrees. Line baking sheets with parchment paper.
In a large bowl sift flour, baking powder, pumpkin pie spice, baking soda, and salt.
In a separate bowl beat butter and sugar for 3 minutes.
Gradually add eggs, one at a time. Add pumpkin and beat until well combined.
In a small bowl, whisk together buttermilk and vanilla.
Slowly add flour mixture to pumpkin mixture, then alternate adding the buttermilk and flour mixture to the pumpkin mixture.
Use a 1 1/2-inch cookie scoop to add batter scoops onto prepared baking sheet, 2 inches apart.
Bake for 15 minutes and allow to cool.
Once cooled pipe filling onto the flat side of one whoopie pie and place another on top.
For the filling:
Beat cream cheese and butter until smooth.
Add creamer and powdered sugar, mix until creamy.