Place candy melts in separate microwave safe bowls and melt in the microwave per the directions on the package.
Place 1 tbsp melted light blue 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 1 tbsp hot chocolate mix, 1 tsp sprinkles, 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.
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, place drizzle the remaining light blue candy melts on top of the assembled hot cocoa bombs followed by the white candy melts, then sprinkle generously with the snowflake sprinkles.
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.
To use the hot cocoa bombs, place them in a mug and pour 2 cups hot milk over the top. Stir until the hot cocoa bombs are completely melted and enjoy!