Football Shaped Whoopie Pies

Name: Football Shaped Whoopie Pies
Prep time: 20 min
Cook time: 8 min
Total time: 28 min
Cuisine: American
Ingredients: 2 cups all purpose flour; 1/2 cup unsweetened cocoa powder; 1 teaspoon espresso powder (optional ); 1 teaspoon baking powder; 1/4 teaspoon baking soda; 1/2 teaspoon kosher salt; 1/2 cup unsalted butter (melted); 1/2 cup granulated sugar; 1/2 cup light brown sugar; 1 large egg (room temperature ); 1 cup whole milk; 1/2 cup unsalted butter (room temperature); 3 cups powdered sugar; 1/4 teaspoon kosher salt; 1 1/2 cups marshmallow fluff (about one 7 ounce jar); 1 teaspoon vanilla extract; 1-2 teaspoons milk (if needed)