To prepare the pies:

1. Preheat the oven to 350 degrees Fahrenheit and line two baking sheets with parchment paper. Set aside.
2. In a large bowl, stir together the oil and brown sugar. Add the pumpkin and egg, stirring until smooth and combined. Add the dry ingredients- flour, salt, baking soda, baking powder, and pumpkin pie spice, stirring gently just until combined. Use a small cookie scoop to scoop out rounds of batter 2” apart on the prepared baking sheets. If your rounds of batter turn out wonky, you can use a slightly wet finger to nudge or smooth the batter into place. Bake them one at a time for about 10 minutes or until a toothpick inserted comes out clean. Allow to cool completely prior to filling.

To prepare the filling:

1. Add ¼ cup of chopped butter into a small saucepan over medium heat. Once the butter has melted begin to stir constantly while you brown the butter. You’ll begin to notice golden flecks at the bottom of the pan and the butter will become nutty and fragrant. Stir and cook just until the butter has become an amber-hued mixture and then pour into a large mixing bowl away from the heat. Add the remaining ½ cup softened butter and stir gently to combine. Set the mixture aside until it has settled to room temperature again.
2. Once ready, use a hand mixer to cream the butter until smooth. Add the powdered sugar, vanilla, and salt, stirring to combine. Add just enough milk, likely a tablespoon or two, to thin the buttercream out to a smooth piping consistency. Spoon the buttercream into a piping bag fitted with a round tip or a freezer Ziploc bag with the end snipped off. Pipe dollops of buttercream onto half of the cookies and sandwich the filling with a second cookie. Enjoy!