2 Preheat oven to 350º F. Line 2 baking sheets with cooking parchment paper.
3 In a large bowl, combine the oil and brown sugar. Add in the pumpkin and eggs, beating well to blend. Add the remaining ingredients and mix well.
4 Drop batter by heaping teaspoons onto the prepared baking sheets. Bake for 10 to 12 minutes. Let cool for 10 minutes on the baking sheets. While still warm, use a spatula to transfer the cakes to a wire rack to cool completely.
6 In a large mixing bowl, cream together cream cheese, egg whites, vanilla, and 1 1/2 cups of confectioners' sugar. Gradually add the remaining confectioners' sugar, beating until light, fluffy and smooth. Refrigerate uncovered for 30 minutes.
8 Place filling on the flat side of half the cakes. Top with remaining cakes, flat side down. Wrap each whoopie pie individually in plastic wrap or waxed paper until ready to serve.