• Preheat oven to 350°F.
• Grease a pair of 6-cup mini cake pans with shortening or butter and dust with flour. Set the pans aside.

Prepare the Cakes

• Whisk the flour, sugar, cocoa powder, baking powder, baking soda, and salt together in a large bowl.
• Add the oil, eggs, vanilla extract, buttermilk, and coffee, and use an electric mixer at low speed to mix everything until combined.
• Use a measuring cup to pour about ¾ cup of batter into each cup in the mini cake pans. They should be about ⅔ full.
• Bake both of the pans of cakes together on the middle oven rack for 25 minutes or until a toothpick inserted into the center of a cake comes out clean.
• Let the cakes cool for about 30 minutes before transferring them to a cooling rack and putting each of them upside down to cool completely.
• Once the cakes have cooled, you can use a sharp knife or 3-inch cookie cutter to even out the sides and bottoms of the cakes, so they are level and straight on the sides.
• Use a 1-inch round cookie cutter or corer to carefully cut 1-inch-deep holes in the middle of each cake, don’t go all the way through the cakes.
• Carefully remove the middle part of each cake but reserve the top part to replace on top of the cream filling. Set the cakes aside.

Make the Marshmallow Cream Filling

• Stir the sugar, water, and corn syrup together in a small saucepan over medium heat.
• Once the mixture starts to simmer, do not stir the mixture anymore, or crystals will form in the syrup. Place a digital candy thermometer in the mixture and let it get to 240°F.
• While the sugar mixture is heating, beat the egg whites with an electric mixer at medium speed in a medium or large bowl until soft peaks form.
• Once the syrup is at 240°F, immediately remove it from heat and pour it into the bowl with the egg whites in a slow, steady stream.
• Once all of the syrup has been added, increase the mixer speed to high and beat until stiff, glossy peaks form.
• Transfer the marshmallow cream to a piping bag and pipe the filling into the middle of each cake. Alternatively, you can spoon the filling into each cake.
• Replace the tops of the holes, then chill the cakes for at least 1 hour.

Prepare the Chocolate Coating

• Combine the chocolate chips and coconut oil in a medium, microwave-safe bowl, and microwave in 30-second increments, stirring between each one, until the mixture is smooth.

Assemble the Ding Dongs

• Line a large baking sheet or cutting board with parchment or waxed paper.
• Coat each cake one at a time by dipping the bottom of each cake into the chocolate, then placing it on a slotted spatula or large fork and spooning the chocolate over the top and sides so it is completely coated and tapping off any excess chocolate back into the bowl.
• Place each cake on the parchment-lined baking sheet or cutting board.
• Once all of the cakes are coated, chill for at least 1 hour or until the chocolate has set.
• Keep the ding dongs in the fridge to keep the chocolate from melting.