Fill a small to medium-sized saucepan with water and place over medium-high heat. There should be enough water to submerge the bottom half of your heat-resistant bowl without overflowing into the bowl itself.
Add your chocolate chips to your heat-resistant bowl and set the bowl in the saucepan. Leave over heat, stirring the chips occasionally, until the chocolate has melted into a thick, smooth liquid -- about 10-12 minutes total.
Dollop a large spoonful of melted chocolate into your half-circle molds one at a time. Using the back of your spoon, smooth the chocolate evenly over the mold.
Place your silicone mold in the freezer and let chill for at least 45 minutes.
Place a small skillet over low heat.
After your chocolate has completely solidified, very carefully pop your half-spheres out of their molds.
Set halves on a chilled plate. Evenly distribute one pack of Swiss Miss powder into three of the six half-spheres. Add around 8-10 mini marshmallows to each of the filled halves.
Pour your milk of choice into the mugs you plan on using to serve your hot cocoa. The mugs should be filled just over halfway. Pour out the mugs into a small saucepan and place over medium to medium-high heat.
Take an empty half-sphere and place rim-down on the skillet for 8-10 seconds or until the chocolate rim is just softened.
Lightly press the softened rim onto a filled half-circle. Use your finger to flatten the smushed-out melted chocolate smooth onto the outer edge -- it looks neater and it works as an edible glue. Once all three spheres are formed, set in the fridge to re-chill.
Pour any remaining Swiss Miss powder from your first pack and the entire second pack into your milk. Mix over heat until completely dissolved. You don’t want your milk to boil, but it does need to be hot enough to crack open the chocolate bombs.
Remove your milk from heat and pour it back into your mugs. Plop a hot chocolate bomb into each mug and watch it work its melty, chocolatey magic. Stir, sip, enjoy!
The trick to strong structural chocolate is in the flick of the wrist. Short spoon strokes can create streaks in the chocolate, which will turn into weak spots as it solidifies. Smooth your melted chocolate into the mold in one or two large, circular motions. If you’re having trouble completely covering the mold, add more melted chocolate.