Whoopie Pies:

Preheat oven to 350° F / 175° C.

Line 2 half sheet rimmed baking trays with parchment or silicone baking mats. Set aside.

In a large mixing bowl, combine flour,  baking soda, baking powder, ground cinnamon, fine sea salt, and ground nutmeg.

In a separate mixing bowl, or the bowl of a stand mixer fitted with paddle attachment, mix softened butter on high speed until smooth and creamy.

Add granulated sugar and light brown sugar and mix until fluffy and well-combined.

Add the mashed bananas, sour cream, egg, and vanilla bean paste, and mix on high speed until well-combined, about 2 minutes.

Gradually add dry ingredients, mixing well after each addition.

With a rubber spatula, fold in the miniature chocolate chips.

Scoop batter into a large piping bag.

Pipe onto prepared trays in 2-inch rounds, allowing 2-3 inches of space for the pies to spread as they bake. You should have about 24 rounds total.

With damp fingertips, pat down the top of each cake to smooth.

Bake in preheated oven, 1 tray at a time, for 15-16 minutes, or until edges are lightly brown and cakes spring back when touched.

Cool completely on trays. Meanwhile, prepare the frosting.

Frosting:

In a large mixing bowl or the bowl of a stand mixer, mix cream cheese, butter, ground cinnamon, and vanilla bean paste on high speed until light and fluffy.

Gradually add the confectioner’s sugar, mixing well after each addition. If necessary, add more confectioner’s sugar to adjust consistency. (Frosting should be smooth and creamy, but not runny.)

Pair cakes by size.

Scoop frosting into a piping bag. Pipe a generous dollop of frosting on the flat sides of half of the cakes.

Place a second cake on top of the frosting to create a sandwich.

Store whoopie pies in an airtight container at room temperature for up to 1 day, or in the refrigerator for up to 3 days.