Melt 2/3 of the chocolate over a double boiler. Remove it from the heat just as it starts to melt and while there are still unmelted chunks of chocolate. Continue stirring off the heat and add the remaining chocolate. White chocolate and dark chocolate will have different melting points.
Once the chocolate is smooth and properly cooled to 82°F, place it back on to simmering water to melt just enough for molding. It is important to keep the temperature of the chocolate within the 82°-90°F range until it is in the mold.
For pink hot chocolate bombs, use white chocolate. At this point, add gel or liquid coloring and mix well, to tint the chocolate. Just a drop of red liquid food coloring is enough to make a nice light pink.
Spread a layer of chocolate inside each sphere and place it in the fridge to set. Gently remove each one and set up your fillings to be able to work quickly.
Melt the edges of one half of the sphere on a heated cast iron pan or plate in the microwave. Fill with hot cocoa mix, festive sprinkles, and marshmallows. Melt the rim of the other half of the sphere and connect the two halves.
Drizzle the tops with melted chocolate and/or add sprinkles or decorations.
place one hot chocolate bomb in a mug or heat-proof cup. Pour 6-8 oz. of steamed milk over the hot chocolate bomb. Stir and enjoy!