Place chocolate candy melts in a microwave safe bowl and melt in the microwave per the directions on the package. If you prefer to melt chocolate with a double boiler you can do that instead.
Place 1 tablespoon melted candy melt into one half of a bomb mold and, using the bottom of your tablespoon measuring spoon, press the chocolate up the sides of the mold, keeping it thick but even. Repeat with 12 bomb mold halves.
Place the chocolate filled bomb molds into the freezer for 5 minutes.
Remove molds from the freezer and gently tap the sides of the mold, pressing on one side of the chocolate to make the chocolate slide out of the mold.
Fill 6 of the molds with 2 tablespoons hot chocolate mix, 1 soft peppermint candy, and 6-8 mini marshmallows.
Heat a plate or a flat-bottom bowl in the microwave until the surface of the plate is warm to the touch, roughly 20-30 seconds.
Press one of the empty chocolate bomb halves open-side-down onto the flat portion of the warm plate for about 10 seconds. This will gently melt the rim of the chocolate cup.
Immediately press this warmed edge chocolate cup to the top of one of the filled cups. This will join the two halves of the hot cocoa bomb.
Using a piping bag or a fork, drizzle the remaining chocolate candy melts over the assembled hot cocoa bombs then immediately follow by sprinkling additional crushed peppermint candies over them.
Place the hot cocoa bombs into the freezer for 5 minutes to get them to set, then remove and store in an airtight container until you’re ready to use.