Preheat oven to 350 degrees. In a medium mixing bowl whisk together the cake mix, eggs, water, and oil. Once combined divide the batter between 18 cupcake liners in pans. Bake 12-15 minutes until a toothpick inserted comes out clean. Set the cupcakes aside to cool completely. Using a teaspoon or even the cap of a soda will work to get the middle out of the cupcake.

In a medium bowl using an electric mixer whip together the butter, marshmallow fluff, powdered sugar, and ¼ of the heavy cream. Fill a Ziploc bag with ¾ of the marshmallow filling. Snip off the tip of the bag and fill each cupcake. Set the filled cupcakes aside.

Next prepare the ganache by putting the chocolate chips and cream in a microwave-safe bowl and microwaving in 30-second intervals until melted and smooth. Carefully dip the tops of the cupcakes in the ganache and set aside to let the ganache set. Meanwhile, transfer the remaining marshmallow filling to another small Ziploc baggie and snip a small end off. Carefully pipe that classic Hostess swirl across the top of each cupcake. Serve!