Melt the milk chocolate in a microwave-safe bowl, stirring every 30 seconds until smooth.
Add 1 tablespoon of the melted chocolate into the molds and use the back of the spoon to spread it across the bottom and up the sides of the dome mold.
Place the molds on a flat surface like a cutting board or baking sheet and freeze for at least 15 minutes. I find the spheres are best to handle and assemble once they’ve had time to really chill in the freezer and 15 – 20 minutes is a good amount.
Gently peel the silicone mold back and pop the half-spheres out. Place them on a piece of parchment paper.
Fill six of the semi-spheres with your hot chocolate mix and marshmallows.
Place a pan over medium heat.
One at a time, take an empty semi-sphere and place it in the hot pan for 2 – 3 seconds until the rim gets melted.
Place the melted rim on top of the semi-sphere filled with cocoa mix and marshmallows and press until attached.
Continue this process until you have 6 cocoa bombs.
Melt the white chocolate in a microwave safe bowl, stirring every 30 seconds.
Transfer to a plastic baggie and cut off the corner.
Drizzle the white chocolate on the hot chocolate bombs.
Add some sprinkles or marshmallows.
Chill for 5 – 10 minutes until the chocolate is set.
Store at room temperature or in the fridge for hotter climates.