Mash the bananas in a medium bowl and set them aside.
Whisk the eggs in a large bowl. Fold the dry ingredients and vanilla into the eggs and stir to combine.
Fold the mashed bananas and vanilla extract into the batter and stir to combine.
Place about 30, similar-sized spoonfuls of batter onto a baking sheet lined with parchment paper, ensuring there are a few inches of space in between each. Bake at 350°F for 13 minutes or until the cookies turn golden brown.
Using a stand mixer or hand mixer, beat the softened cream cheese and powdered sugar together until smooth.
Pipe the frosting onto one of the cookie halves and sandwich it with another one. Repeat until you run out of cookies. Store the whoopie pies in the refrigerator until you're ready to serve (avoid using an airtight container or they will turn soggy). Enjoy!