Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a bowl, whisk together flour, baking powder, baking soda, salt, and pumpkin pie spice.
In another bowl, mix pumpkin, oil, brown sugar, egg, and vanilla until smooth.
Gradually add dry ingredients to wet ingredients, mixing until combined.
Drop spoonfuls of batter onto prepared baking sheet. Bake for 12-15 minutes, until edges are set. Cool completely.
For the filling, beat butter until creamy. Add powdered sugar and vanilla, beating until smooth. Fold in marshmallow creme.
Spread filling on flat side of one cookie, then top with another cookie. Repeat with remaining cookies.