Preheat the oven to 350 degrees F. Line a muffin tin with paper or foil liners and set it aside.

Put the softened butter and chopped chocolate in a heat-proof bowl over a saucepan of simmering water.

Stir the butter and chocolate together until they are completely melted and combined.

Whisk the brown sugar, vanilla extract, and hot chocolate mix into the chocolate and butter. Remove the bowl from the heat, set it aside, and allow it to cool slightly.

After the chocolate mixture has cooled slightly, whisk in the eggs one at a time, making sure that they are each thoroughly combined before adding another.

Whisk in the flour, salt, and baking powder.

Divide the batter among the prepared muffin tins.

Bake for 20-25 minutes, or until a toothpick, when inserted into the center, comes out mostly clean.

Allow the cupcakes to cool in the pan for 10 minutes before removing them to a wire rack to finish cooling completely.

Once they have cooled, use a paring knife to cut out the centers of the cupcakes (be careful to not cut all the way through to the bottom). Remove the cupcake innards (snack for later!).

Fill the cupcake holes with marshmallow creme until level, or just about level, with the top of the cupcake.

Place the mixing bowl and beaters/whisk attachment in the fridge for 10-15 minutes.

Add the water to a small microwave safe bowl and sprinkle the gelatin on top. Allow it to sit for a few minutes.

Transfer the gelatin mixture to the microwave and microwave until the gelatin is fully dissolved, this will only take 10-15 seconds. Stir the mixture, then set it aside to cool slightly.

In the refrigerated bowl of a stand mixer fitted with the whisk attachment (or in a large mixing bowl, using an electric mixer) combine the heavy whipping cream, powdered sugar, and vanilla extract.

Whip the cream until it starts to thicken and soft peaks form. Turn the mixer to low speed.

Slowly pour the gelatin mixture in until it is well combined. Increase the mixer to medium speed and continue mixing until stiff peaks form.

Pipe the whipped cream frosting onto the prepared cupcakes.

Garnish the cupcakes with shaved chocolate, if desired.