Dorie Greenspan's Les Whoopies | La Cucina Grandinetti

Ingredients

• 2 cups (272 grams) all-purpose flour
• 1/2 cup (42 grams) unsweetened cocoa powder (preferably Dutch-processed)
• 1-1/4 teaspoons baking soda
• 1/4 teaspoon baking powder
• 1/2 teaspoon fine sea salt
• 1 stick (8 tablespoons; 4 ounces; 113 grams) unsalted butter, at room temperature
• 1/2 cup (100 grams) sugar
• 1/2 cup (100 grams) packed light brown sugar
• 1 large egg, at room temperature
• 1/2 teaspoon pure vanilla extract
• 1 cup (240 milliliters) whole milk, at room temperature
• 1-1/2 sticks (12 tablespoons; 6 ounces; 170 grams) unsalted butter, at room temperature
• 1 cup (256 grams) creamy peanut butter (not natural)
• 1 cup (120 grams) confectioners’ sugar
• 1 teaspoon pure vanilla extract
• 4 ounces (57 grams) bittersweet or semisweet chocolate, finely chopped
• 1/4 cup (60 milliliters) heavy cream