For the Carrot Cake Whoopie Pies

1. Preheat your oven to 350 degrees Fahrenheit. Line baking sheets with parchment paper. This is incredibly important to ensure the sticky whoopie pies do not stick to the pan.
2. In a medium bowl, use a wire whisk to mix all purpose flour, baking powder, baking soda, salt, cinnamon, nutmeg, and ground ginger together until combined.
3. In a large bowl, mix granulated sugar, light brown sugar, vegetable oil, room temperature egg, and room temperature sour cream together with a wire whisk until smooth.
4. Pour the dry ingredients into the large bowl of wet ingredients. Carefully mix the ingredients together with a whisk. Do not mix past when you see the flour pieces disappear into the batter. Overmixing could lead to dense cake disks.
5. Add chopped carrots into the batter and mix until evenly distributed. Let the batter rest at room temperature for 10 minutes to firm up and gain structure.
6. Divide the batter into 1-tablespoon-sized dollops on your prepared pans. Make sure the batter dollops are at least 2 inches apart on the pans.
7. Bake for 9-12 minutes until the tops are domed and shiny, the edges are light golden brown, and a toothpick inserted into the center of one of the cake pieces comes out with a few crumbs.
8. Allow the cake pieces to cool before frosting.

For the Cream Cheese Filling

1. In a large bowl with a hand mixer or in the bowl of a stand mixer that is fitted with a paddle attachment, beat the room temperature butter and cream cheese together on high speed until smooth.
2. Add powdered sugar to the mixture, and beat on low speed to avoid spilling the powdered sugar. Scrape down the sides and the bottom of the bowl with a rubber spatula to ensure all of the ingredients are properly incorporated.
3. Add marshmallow fluff to the frosting. Beat on high speed for 2-3 minutes until the frosting becomes velvety, smooth, and bright white in color. For more control, transfer the frosting to a piping bag or zippable plastic bag with the corner cut off of it if desired.

For Assembly

1. Frost half of the cooled cake disks with the cream cheese frosting.
2. Top an unfrosted cake piece on top of the frosting to create a cake sandwich. If you have time, let them rest and firm up at room temperature for 30 minutes before serving or storing.
3. Individually wrap them in cling wrap before storing them at room temperature for up to 2 days, in the fridge for up to 4 days, or in the freezer for up to 4 months.