Using a large bowl or a stand mixer with the paddle attatchment cream together the softened butter, Saratoga Peanut Butter, light brown sugar, and white granulated sugar well combined. Add the egg, dried pumpkin puree, and vanilla extract, then whisk until fully incorporated.

In a separate bowl, whisk together the all purpose flour, whole oats, baking powder, baking soda, and salt. Add the dry ingredients to the pumpkin peanut butter mixture, stirring until just combined.

Using a cookie scoop, portion the dough into 12 cookie dough balls onto the prepared baking sheets, leaving about 2 inches between each cookie. *see note*

Bake for 14-16 minutes, or until the edges are lightly golden and the centers look set but still soft. Immediately after removing from the oven, swirl with a large cup to create a perfect circle if desired.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

In a large bowl, beat the softened butter and marshmallow filling with an electric mixer until light and creamy, about 2 minutes. Gradually add the powdered sugar and mix until smooth.

Add the heavy whipping cream, vanilla bean paste, and a pinch of salt. Continue mixing for 1–2 minutes, until the marshmallow buttercream is fluffy and smooth.

Once the pumpkin peanut butter oatmeal cookies are completely cooled, pipe or spread a generous layer of marshmallow buttercream onto the flat side of half of the cookies. Top each frosted cookie with another cookie and gently press together to create soft pumpkin peanut butter oatmeal cream pie cookies.