Using a double boiler or the microwave melt half of the chocolate. If using the microwave stir after 15 second intervals.
Spoon about 1 Teaspoon of the chocolate into each dome in the mold.
Using a small pastry brush, brush the chocolate evenly all over the dome and up the sides of the mold - all the way to the top of the edges. Pop into the freezer for 10 minutes on a baking sheet to help set.
Remove from the freezer and spoon another dollop of chocolate into the domes, one at a time. Brush the chocolate all over before moving onto the next. Freeze again for another 10 minutes.
Fill half the domes with hot chocolate mix (about 1-½ Teaspoons) then top with mini marshmallows (about 4-5 works well).
Heat a plate on top of a pan of hot water. Press one of the empty domes onto the plate to melt the edges. (about 30 seconds)
Press onto filled dome. Hold while the chocolate seals. Freeze to seal quicker.
Decorate the hot chocolate bombs how you wish. I use more melted chocolate and sprinkles.
Notes
When making these hot chocolate balls it's best to use two layers of chocolate. It helps thicken the edges and won't be as easy to break. My hot chocolate bombs were made using a mold with 2" domes. You can change this recipe up and use anything you like. I've heard of crushed candy canes, oreo cookies, espresso... amongst other things being used. The recipe I have listed is your basic go-to for a good hot chocolate bomb but can be changed up to your preference.I used milk chocolate, but depending on your own taste you could use semi-sweet chocolate or dark chocolate. I used baking chips to make it economical but if you want to go all out you could go for a more expensive chocolate.Whole milk, 2% or fat free can be used to make the hot chocolate.