Preheat oven to 350 degrees. Line a baking sheet with parchment paper.
In a medium bowl, combine the flour, baking powder, and salt. Whisk till combined. Set aside.
In the bowl of a stand mixer, add in the butter, brown sugar and granulated sugar. Beat until light and fluffy (about 2 minutes).
Add in the egg and maple extract, and beat on medium until combined, scraping down the sides of the bowl as needed.
Add in the old fashioned oats and beat until just combined.
Slowly, add in the flour, baking powder and salt. Mix until combined.
Using a 1 1/2 tablspoon cookie scoop, scoop out cookies and place on the prepared pan. Lighly press the cookies down so they're no longer domed, and slighly flattened.
Place in the preheated oven and bake for 10 to 11 minutes until the edges are golden brown.
Remove from oven, and let the cookies cool for 10 minutes on pan before moving them to the wire cooling rack.
While the cookies are cooling, make the maple cream filling:
In the bowl of a stand mixer, cream the butter, then add the maple extract and heavy cream - blend well.
Add the powdered sugar, mixing on low until almost completely combined. Then turn the mixer on high and beat for another 2 - 3 minutes until the filling becomes light and fluffy.
Once the cookies are completely cooled, add the filling to a piping bag and cut off a corner. Pipe filling onto cookie and then add the top cookie to the oatmeal maple cream pie.