• Preheat oven to 375°F. Line two baking sheets with parchment paper.
• In a medium bowl, whisk the flour, cocoa powder, baking soda, and salt until combined.
  2 1/4 cups all-purpose flour, 3 Tablespoons unsweetened cocoa powder, 1 1/4 teaspoons baking soda, 1/2 teaspoon salt
• In the bowl of a stand mixer, beat the butter and brown sugar for 2 minutes using the paddle attachment until light. Add egg and beat again.
  1/2 cup salted butter, 1 cup light brown sugar, 1 large egg
• Alternate adding the flour mixture with the buttermilk, vanilla, and red gel food coloring, beating after each addition and scraping the sides of the bowl, just until combined. Stir in chocolate chips.
  3/4 cup buttermilk, 2 teaspoons vanilla extract, 1 teaspoon red gel food coloring, 1/2 cup semisweet chocolate chips
• Use a small scoop to drop batter onto the parchment-lined baking sheets, spacing them 2-3 inches apart.
• Bake for 10 to 12 minutes, until just done around the edges and the tops bounce back when lightly touched. Cool on the baking sheet for 5 minutes before transferring the cookies to a wire cooling rack to cool completely.

Prepare the Cream Cheese Filling:

• Combine the cream cheese and butter in a bowl and beat using an electric mixer until smooth. Add the powdered sugar, 1 cup at a time, mixing until combined. Add vanilla and salt and beat until smooth. Transfer to a piping bag fitted with a round tip.
  4 ounces cream cheese, 1/4 cup salted butter, 3 1/2 cups powdered sugar, 1 teaspoon vanilla extract, Pinch of salt

Assembly:

• Pipe a layer of cream cheese filling onto the flat side of one cookie, then top with another cookie to make a whoopie pie.
• Store in an airtight container for up to 1 week.