Dump melting wafers into a microwaveable bowl and heat in 30 second increments, stirring in between each heat session, until fully melted.
Add a spoon full of chocolate in one cavity of the silicone mold, using the spoon (or a pastry brush) to cover the entire cavity with chocolate, making sure to get all the way up the sides. Do this until all 12 cavities in both of the molds are covered in chocolate.
Place chocolate covered molds in the freezer for 5 minutes.
Remove molds from the freezer and repeat step 3 to add a second layer of chocolate. Place in freezer for 5 minutes.
Remove the plate and the molds from freezer, and carefully remove each of the chocolate spheres. Set them on the cold plate.
Fill 6 of the chocolate spheres, each with 1 tablespoon of hot cocoa mix and 6-8 mini marshmallows.
Heat a small plate in the microwave for 2 minutes. Remove
Place one of the empty chocolate spheres upside down on the plate and gently move it around to melt the chocolate a bit. Place one of the empty spheres to attach to a filled sphere and use your finger and chocolate to seal the two ends together, or pipe chocolate to seal the ends. Set on the cold plate.
Add purple and green sprinkles to a small bowl and mix together.
Put some of the melted chocolate into a piping bag or ziplock baggie and snip the very end off with a scissors.
Pipe chocolate in a back and forth motion on top of each of the cocoa bombs and add purple and green sprinkles, then sprinkle with a light dusting of the sanding sugar.
To enjoy, place in a mug and pour in 6 oz of hot milk. You may also add an additional tablespoon of cocoa mix to your mug, if desired.