1. Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
2. In a medium bowl, whisk together flour, baking powder, baking soda, cinnamon, ginger, cloves, and salt.
3. In a large bowl, cream together butter, granulated sugar, and brown sugar until light and fluffy. Beat in egg and vanilla extract.
4. In a small bowl, combine pumpkin puree and buttermilk.
5. Gradually add dry ingredients to wet ingredients, alternating with pumpkin mixture, beginning and ending with dry ingredients. Mix until just combined.
6. Drop by rounded tablespoons onto prepared baking sheets.
7. Bake for 10-12 minutes, or until edges are lightly golden.
8. Let cool on baking sheets for a few minutes before transferring to a wire rack to cool completely.

For the Filling:

1. In a large bowl, cream together butter and powdered sugar until light and fluffy.
2. Beat in vanilla extract. Gradually add milk until desired consistency is reached.

Assembly:

1. Spread filling on the flat side of one whoopie pie and top with another whoopie pie.