Preheat oven to 350°F. Line 24 cupcake tins with cupcake liners. Set aside.
In a large bowl, whisk together sugar, cocoa powder, flour, baking soda, baking powder, and salt. In a separate bowl, whisk oil, vanilla, eggs, and buttermilk.
Pour the dry ingredients into the wet, whisking until no lumps remain. Pour in brewed coffee, mixing until just combined.
Use 1/3 cup measuring cup or a large ice cream scoop to divide the batter evenly between the cupcake liners, filling them about 2/3 of the way. Bake for roughly 25 minutes, or until a knife inserted in the center of the cupcake comes out clean. Cool completely on a wire rack before filling.
While the cupcakes cool, make the marshmallow cream filling. In a stand mixer fit with the paddle attachment, combine the butter, marshmallow fluff, powdered sugar, vanilla extract, and salt. Start the mixer on low speed gradually increasing to medium high. Beat for 1 minute or until light and fluffy.
Transfer the frosting to a piping bag and snip off the end of the bag. Insert the pastry tip into the top of each cupcake and and firmly squeeze a few tablespoons of the marshmallow cream into the center until the cupcake starts to expand ever so slightly on the top.
Next, make the chocolate ganache. In a microwave safe bowl heat up the heavy cream for 20 to 30 seconds or until scalding. Add the chocolate to the heavy cream and stir. Let the mixture sit for 30 seconds to allow the chocolate to melt and then mix until smooth and fully melted.
Dip the top of each cupcake into the chocolate ganache, shaking off any excess so that only a thin coating remains over the top. Place back on the cooling rack for the ganache to fully set.
While the ganache sets make the vanilla icing for the loops on top. Combine the powdered sugar, milk, vanilla, and salt in a small bowl and whisk to combine until smooth. Transfer to a piping bag fit with a small round tip. Once the ganache is set, pipe loops on the top of each cupcake. Enjoy!