2 ½ c. all-purpose flour
1 ¼ t. baking soda
¼ t. salt
1 c. granulated sugar
½ c. butter, softened
1 egg
2 t. vanilla
¾ c. buttermilk
½ c. rainbow sprinkles (jimmies, not non-pareils)
Preheat oven to 375 degrees F. Line baking sheets with parchment paper.
In a medium bowl, whisk the flour, baking soda, and salt until combined.
In a bowl of a stand mixer, beat the butter and sugar for 2-3 minutes until light. Add the egg and vanilla and beat again.
Alternate adding the flour mixture and the buttermilk, beating after each addition, and scraping the sides of the bowl, just until combined. Gently stir in sprinkles.
Use a small scoop to drop batter onto parchment lined baking sheets spacing 2-3 inches apart. Bake for 10-12 minutes until just done around the edges and top bounces back when lightly touched. Cool on the baking sheet for 5 minutes. Transfer to cooling rack.
Prepare your favorite frosting. Pipe a layer of frosting onto the flat side of one cookie, then top with another cookie to make the whoopie pie. Roll edges in additional sprinkles if desired.