Melt your chocolate in the microwave for a minute, then in 20-second increments as needed.
To make the cocoa bombs green add a few drops of green food coloring into your melted chocolate and stir. A little goes a long way and you can add gradually to achieve the desired shade.
Using a spoon, add about a tablespoon of your melted chocolate into the mold cavity, then using the spoon spread it to the rim of the mold. Make sure that the edges are thick enough.
After filling the mold, add to the freezer for 10-15 minutes.
Heat a plate in the microwave (or a pan on the stovetop). Pop out the chocolate shell from the mold, removing all 6 and setting aside. If you have some that crack a little it's ok, using the hot plate will trim them down. If any crack to an extent you can't use them, set aside and you can remelt them to try again.
Take one of the shells and slide and twist it around on the hot plate, melting the edges. Add about a tablespoon of hot cocoa mix, marshmallows and any other additions like sprinkles or candy cane bits to the inside of the shell.
To make this a Grinch Hot Cocoa Bomb, add a heart marshmallow to the inside of the cocoa bomb.
Press the two shells together, placing the empty one on top of the shell filled with cocoa and marshmallows. If there are gaps in the edges, use a little of the extra melted chocolate on the plate and fill with your finger.