Preheat oven to 350F. Grease whoopie pie pan and set aside.
In a medium mixing bowl, combine flour, baking soda, baking powder, salt, cinnamon, and nutmeg.
2 cup flour, 1 ½ tsp baking soda, 1 tsp baking powder, 1 ½ tsp cinnamon, ½ tsp kosher salt, ¼ tsp nutmeg
In another large mixing bowl, beat butter, granulated sugar, and brown sugar until light and fluffy. Add eggs one at a time and beat for a minute. Add vanilla extract. Stir in shredded carrots and beat on low speed until combined. Add the flour mixture to batter and mix until just combined.
½ cup butter, ½ cup brown sugar, ½ cup sugar, 2 large egg, 2 tsp vanilla extract, 1 ½ cup carrot
Use an ice cream scoop to drop batter into each whoopie pie cavity. Bake for 10-12 minutes or until an inserted toothpick comes out clean.
Cool the cookies on a wire rack for 20-25 minutes.
While the cookies cool, make the cream cheese filling. In a large mixing bowl, beat together on medium speed the cream cheese, butter, heavy cream, vanilla extract, and salt until smooth and fluffy. Slowly add the powdered sugar until combined. Transfer the frosting to a piping bag or a Ziploc bag with a snipped corner.
8 oz cream cheese, ½ cup butter, 2 tbsp heavy cream, 1 tsp vanilla extract, ¼ tsp salt, 4 cup powdered sugar
Once the cookies have fully cooled, pipe a little filling onto a cookie and sandwich it with another cookie on top. Repeat with remaining cookies.
Notes
Store in the fridge for up to 7 days or freeze for up to 3 months.You can also use a baking sheet with parchment paper if you don't have a whoopie pie pan.