My filling did not come together in a thick wonderful way that would be perfect for whoopie pies, but instead was a bit thin. I would recommend letting the butter and cream cheese only sit out for 30 minutes before whipping it up.
2cupscoarsely grated zucchini1 good sized zucchini
2 1/2cupsflour
1 1/4teas baking soda
1 1/2teas cinnamon
3/4teas ginger
1/2teas nutmeg
3/4teas saltdivided
3/4cupbuttermilk
2teas vanilladivided
1stick unsalted butterplus 1/2 stick, softened
1cuplight brown sugarpacked
1egg
1cupwalnutschopped
8ozpackage cream cheesesoftened
1 1/2cupsconfectioners sugar
Instructions
Preheat the oven to 350 degrees F. Line two baking sheets with parchment paper and set aside.
Using a kitchen towel, squeeze any excess water from zucchini.
In a large bowl, whisk the flour, baking soda, spices, and 1/2 teas salt.
Beat the 8 tbs butter and sugar in the bowl of your stand mixer about 5 minutes, until light and fluffy. Scrape the sides and mix in the egg.
Add the flour mix alternating with the buttermilk, beginning and ending with the flour until combined. Fold in the zucchini and walnuts.
Drop 1/4 cup portions of the batter onto the prepared baking sheets, leaving a 2" boarder between each, and bake for 18 to 22 minutes. Let cool on the pan for 5 minutes before transfering to a wire rack to cool completely.
Meanwhile, make the filling by beating the cream cheese and remaining 4 tbs butter together until smooth.Add the confectioners' sugar, vanilla, and remaining 1/4 teas salt. Mix until smooth.
Arrange cookies so that half are facing flat side up and spread cream cheese filling over them. Top with the remaining cookies and serve. (Keep chilled in fridge if not eating right away).