- 2 cups all-purpose flour
- 3 tablespoons unsweetened (natural) cocoa powder (not Dutch process)
- 1/2 teaspoon baking soda
- 1/2 teaspoon salt
- 1/2 stick (1/4 cup) unsalted butter, softened
- 1/4 cup vegetable oil
- 1 cup sugar
- 1 large egg
- 1 teaspoon vanilla
- 1 teaspoon distilled white vinegar
- 2/3 cup well-shaken buttermilk
- 1 (1-ounce) bottle red food coloring (2 tablespoons)
- 8 ounces cream cheese, softened
- 1/2 stick (1/4 cup) unsalted butter, softened
- 1 teaspoon fresh lemon juice
- 1/2 teaspoon vanilla
- 1/8 teaspoon salt
- 2 cups confectioners' sugar
- Preheat oven to 350°F with racks in upper and lower third. Line two baking sheets with parchment paper.
- Whisk together flour, cocoa powder, baking soda, and salt in a bowl.
- Beat butter, oil, and sugar with an electric mixer until combined well, about 2 minutes. Beat in egg, vanilla, and vinegar.
- Reduce speed to low and alternately mix in flour and buttermilk in batches, beginning and ending with the flour until combined.
- Add the red food coloring and mix on low speed until thoroughly combined.
- Spoon 2 tablespoon mounds of batter 2-inches apart on lined baking sheets.
- Bake, switching positions of baking sheets halfway through baking, until rounds are puffed and set, 8 to 10 minutes.
- Slide parchment with rounds onto wire racks to cool completely.
- Beat together cream cheese, butter, lemon juice, vanilla, salt, and sugar until creamy, 1 to 2 minutes. Spread about 2 tablespoons of filling on flat-side of half the rounds; top with remaining rounds, flat side down, to form whoopie pies.