Start by obtaining a sphere that you can mold your hot chocolate bombs to. Ideally, it should be as large as a lime, but small enough that it fits in a standard mug. I used a Christmas ornament for my mold. If your object is not clean, or can't be washed, wrap it tightly in saran wrap first
To make your mold, take two sheets of tin foil and fold them in half. Use both sheets to form around the object tightly, creating two half spheres. Fold back the extra foil so that you have a clean line to form the edges.
In a microwave-safe mixing bowl, add 1 C of chocolate and microwave in 20-second intervals, mixing each time, until the chocolate is melted but not too hot
Paint the chocolate into both halves of the mold, ensuring that it covers the foil evenly. Place the molds into the freezer for 5-10 minutes and then paint a second coat of chocolate onto the edges and anywhere that seems thin. Freeze for another 5-10 minutes
Gently peel the foil off of the chocolate to remove the mold. If the chocolate starts cracking, paint more on to the affected areas and re-freeze
Once you have two chocolate halves, fill one half with 1-2 tbsp of hot chocolate mix, mini marshmallows, and any other toppings you desire
If needed, heat up the second cup of chocolate the same as before. Scoop the melted chocolate into the corner of a small ziplock bag and snip a very small hole in the corner of it
Set your empty half shell on top of your filled shell, and use the "piping bag" of chocolate to attach the two halves. Use your paintbrush as needed to smooth out or fill any gaps. Place back into the freezer for another 5-10 minutes
Once your chocolate bomb is formed, use the remaining bag of chocolate to drizzle on top, and decorate with any sprinkles, crushed candy canes, caramel, or toppings desired.
Keep these hot chocolate bombs separate from each other and safe from the heat of your hands by storing them each in their own cupcake liner
When ready to use, heat a mug of milk in the microwave for 2 minutes and drop your hot chocolate bomb in. Stir as necessary