Ingredients:
For the chocolate cupcakes:
1 cup all-purpose flour 
1 cup granulated sugar 
½ cup unsweetened cocoa powder 
1 tsp baking soda 
½ tsp baking powder
½ tsp salt 
1 large egg 
½ cup buttermilk 
½ cup vegetable oil 
1 tsp vanilla extract 
½ cup hot water 
For the cream filling:
½ cup unsalted butter, softened 
1 cup powdered sugar
1 cup marshmallow fluff 
1 tsp vanilla extract
For the chocolate ganache:
1 cup semi-sweet chocolate chips
½ cup heavy cream
For the signature white swirl:
½ cup powdered sugar
1-2 tbsp milk
½ tsp vanilla extract
Instructions:
Preheat the oven: Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners. 
Make the cupcake batter: In a large bowl, sift together the flour, sugar, cocoa powder, baking soda, baking powder, and salt. In a separate bowl, whisk together the egg, buttermilk, vegetable oil, and vanilla extract. Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Stir in the hot water until the batter is smooth and thin. 
Bake the cupcakes: Fill each cupcake liner about ⅔ full with the batter. Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean. Let the cupcakes cool completely on a wire rack. 
Prepare the cream filling: In a medium bowl, beat the softened butter until creamy. Add the powdered sugar and marshmallow fluff, beating until smooth. Mix in the vanilla extract. Transfer the cream filling to a piping bag fitted with a small round tip. 
Fill the cupcakes: Once the cupcakes are completely cool, use a small knife or cupcake corer to cut out a small hole in the center of each cupcake. Pipe the cream filling into each cupcake, then cover the hole with a piece of the cut-out cake. 
Make the chocolate ganache: Heat the heavy cream in a small saucepan until just simmering. Pour the hot cream over the chocolate chips in a bowl, let sit for a minute, then stir until smooth. Let the ganache cool slightly before dipping the top of each cupcake in the ganache. Allow the ganache to set for 10-15 minutes. 
Make the white swirl icing: In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth and pipeable. Transfer the mixture to a piping bag fitted with a small round tip or a ziplock bag with the corner snipped off. Pipe the signature swirl design on top of each cupcake. 
Serve and enjoy: Let the ganache and icing set completely before serving. Enjoy your homemade Hostess cupcakes! 
Prep Time: 30 minutes | Baking Time: 20 minutes | Total Time: 50 minutes
Calories: ~300 kcal per cupcake
Servings: 12 cupcakes