Mix 1 box chocolate cake mix along with ingredients needed to make the cake: eggs, oil and water according to the directions on the back of the box.
Add the cake batter to 24 cupcake liners and bake for 14-19 minutes or per the directions on the back of the box.
Cool the cupcakes for 10 minutes in the cupcake tin. Take them out and cool them completely on a wire rack.
In a large bowl with an electric hand mixer or in the body of a stand mixer with the paddle attachment, whip 6 Tablespoons unsalted butter, softened until smooth.
Add 7.5 ounces marshmallow creme and mix until smooth.
Add 1 1/2 cups powdered sugar a little at a time until fully combined.
Add 5 Tablespoons heavy cream and whip until smooth for 3 minutes. Reserve ⅓ cup on the side for the topping.
Place the filling into a piping bag fitted with an open round tip (I used Wilton 12).
Gently press the tip into the top of the cupcake and squeeze. You will see the cupcake puff up slightly, if you add too much, the cupcake will split. Continue with all of the cupcakes. If any filling starts to come out the top, just scrape it off with a butter knife.
In a heatproof bowl, add 6 ounces milk chocolate chips.
Warm 1/3 cup heavy cream to scalding (180°F), and pour over the chocolate chips. Let it sit for 5 minutes, then whisk until smooth.
Add 1/2 teaspoon vanilla extract and stir to combine.
Take a spoon and add about 1 teaspoon of this chocolate ganache on top and roll it around to coat the top of the cupcake. Place them back on the wire rack and let them set up for 15 minutes.
Once set, add the remaining filling to a piping bag fitted with a small round open tip (I used Wilton 2). Pipe curly-q’s on top of each cupcake and serve.
If the ganache starts to get too thick while adding the topping, pop the bowl in the microwave for a few seconds to loosen it back up.
You can use semisweet or dark chocolate chips in place of milk chocolate.
Best eaten at room temperature but leftovers need to be refrigerated.
Keep leftovers in the fridge for up to 1 week, freeze for up to 3 months.