Place a spherical mold(s) into the freezer while you are melting the chocolate.
You can melt the chocolate by following the directions on the package to melt the chocolate in the microwave in a microwave-safe bowl OR you can set up a double boiler.
Once the chocolate is melted, remove the mold(s) from the freezer and place on a small baking sheet.
Add 1 tablespoon of the melted chocolate into the mold. Use your spoon to move the chocolate around the inside of the mold. Make sure that you apply the chocolate evenly.
Repeat the process for the remainder of the molds. When you are done, lightly tap the mold(s) to get any air bubbles out.
Place the mold(s) on the baking sheet back into the freezer and let the chocolate spheres set up for 10 - 15 minutes.
Remove the chocolate bomb molds from the freezer and carefully remove the chocolate spheres from the mold.
There are three methods for melting the rim of each sphere to even them out and for attaching the top half-shell to the bottom one:
Method 1: Pour some melted chocolate into a disposable piping bag, then pipe it around the edge of the bottom shell. Carefully place the top shell onto the bottom one and gently hold them in place for 30-60 seconds to allow the piped chocolate to harden and "glue" the pieces together.
Method 2: Warm up a shallow frying pan on the stove. Place a piece of wax paper into the pan, and holding the top half-shell, rub gently on the wax paper until the edges start to melt a bit. Use this to then stick the top to the bottom, holding together until set
Method 3: Heat a plate in the microwave for approximately 60 seconds. Remove from the microwave then place it directly onto the hot plate for 5 to 10 seconds. You just want the rim to gently melt.
Whichever method you use, carefully pick up the bomb and make sure that there are no gaps around the middle of the chocolate bombs.
Fill the molds with 1 tablespoon of the hot chocolate powder mix and top with mini marshmallows.
Attach the top shell to the filled bottom shell using one of the desired methods above.
Repeat the process until you've made all of the chocolate bombs.
To decorate with edible gold dust, dip a paintbrush into the dust and paint as much or as little as you want onto the hot cocoa bomb.
Melt ½ cup of the red wafers and either fill a squeeze bottle to drizzle the chocolate over the hot cocoa bombs, fill a disposable piping bag or plastic food bag with the corner snipped off or use a fork dipped into the melted candy and drizzle it over the bombs.
Top with gold sprinkles.
To use the bomb, place it in a large mug, pour warm milk over it, and stir until everything is mixed together.