Pistachio-Cardamom Whoopie Pies with Rosewater Buttercream

Ingredients

• 1.5 teaspoons double-acting baking powder 
• 0.8 cup brown sugar packed ()
• 1 cup buttermilk 
• 2 cups powdered sugar 
• 1 large eggs 
• 3 cups flour all-purpose
• 0.8 cup granulated sugar 
• 1 teaspoon ground cardamom 
• 3 tablespoons cup heavy whipping cream (whipping)
• 0.8 cup pistachios 
• 3 drops food coloring red
• 1 teaspoon rosewater 
• 0.1 teaspoon salt 
• 4 tablespoons butter unsalted at room temperature
• 1 teaspoon vanilla extract 

Equipment

• bowl
• baking sheet
• baking paper
• oven
• knife
• stand mixer
• pastry bag

Directions

1. For the Pistachio-Cardamom Whoopies: Position a rack in the center of the oven and preheat the oven to 350ºF. Line two baking sheets with parchment paper.
2. Sift together the flour, baking powder, cardamom, and salt onto a sheet of waxed paper.
3. In the work bowl of a stand mixer fitted with the paddle attachment, beat together the butter and both sugars on low speed until just combined. Increase the speed to medium and beat until fluffy and smooth, about 5 minutes.
4. Add the egg, beating well.
5. Add the vanilla.
6. Add half of the flour mixture and half of the buttermilk to the batter and beat on low until just incorporated. Scrape down the sides of the bowl.
7. Add the remaining flour mixture and 1/2 cup buttermilk and beat until completely combined.
8. Add the pistachios and mix just until combined.
9. Using a small ice-cream scoop or 2-tablespoon scoop, drop about 2 tablespoons of batter onto one of the prepared baking sheets and repeat, spacing them at least 2 inches apart.
10. Bake one sheet at a time for about 10 minutes each, or until the cakes begin to brown.
11. Let the cakes cool on the sheet for at least 5 minutes before transferring them to a rack to cool completely.
12. For the Rosewater Buttercream Filling: In the work bowl of a stand mixer fitted with the paddle attachment, beat together the confectioners’ sugar and the butter, starting on low and increasing to medium speed, until the mixture is crumbly, about 1 minute.
13. Add the heavy cream, rosewater, vanilla, salt and red food coloring and beat on high until smooth, about 3 minutes.
14. Spread the filling onto the flat side of one cake using a knife or spoon. Top it with another cake, flat-side down. Repeat with the rest of the cakes and filling.Alternatively, you can use a pastry bag with a round tip to pipe the filling onto the cakes, which will give you a smoother, neater presentation.