½cup(113 g or 1 stick) unsalted butter, room temperature
1cup(200 g) light brown sugar
1large egg, room temperature
1teaspoonpure vanilla extract
¾cup(180 ml) buttermilk, room temperature
1teaspoongel red food coloring, (see notes)
Cream Cheese Filling
1cup(225 g or 8 oz) block-style cream cheese, room temperature
¼cup(57 g) unsalted butter, room temperature
2cups(240 g) confectioners’ sugar, sifted
½teaspoonpure vanilla extract
Pinchof salt
Instructions
Preheat oven to 350℉. Line a baking sheet with parchment paper and set aside.
In a large bowl, whisk together flour, cocoa powder, baking soda and salt. Set aside.
In the bowl of a stand mixer (or using a hand mixer), beat butter and brown sugar on medium-high speed until light and fluffy, about 3 minutes. Add egg, vanilla and red food gel. Mix in the buttermilk (it’s okay if it looks a little curdled). Scrape down the sides of the bowl as needed.
Add the dry ingredients to wet ingredients and mix just until combined.
Use a medium cookie scoop to transfer batter to prepared pan, leaving 2 inches of space between each scoop. Bake at 350℉ for about 10 to 12 minutes. They are done when they are soft and slightly springy. Transfer to a wire rack to cool completely.
In the bowl of a stand mixer (or using a hand mixer), beat cream cheese and butter until creamy. Add confectioners’ sugar and mix until combined. Finally, mix in vanilla and a pinch of salt.
Transfer frosting to a piping bag fitted with desired tip. Match up the whoopie pies so the pairs are similar size. Pipe frosting to the bottom of one cookie, then press the bottom of the matching cookie gently on top to create a sandwich. Repeat with remaining cookies.
Notes
Red food dye: Gel dye is best because it's more concentrated and creates a stronger color. If using liquid dye, increase the amount to 2 teaspoons or more until desired color is reached. Remember the color will lighten up a little bit when baked.Store whoopie pies in an airtight container in the refrigerator for up to 1 week. I suggest placing parchment paper between layers so the sandwiches don't stick.