Optional: sprinkles, colored sanding sugar, and melted candy melts
Directions
Melt the chocolate in the microwave in short bursts, stirring between each, until smooth. Do not let it go over 90°F.
Brush a thin coat inside 2-1/2-inch silicone sphere molds and chill until set, then add a second coat. Keep the remaining chocolate in a piping bag.
Pop the shells out of the molds. Whisk together the cocoa, milk powder and confectioners' sugar, then fill six shells with 3 tablespoons each and top each with 1 tablespoon of marshmallow bits.
Pipe melted chocolate around the rims of the filled halves, press the empty halves on to seal, decorate if you like, and chill until firm.
Notes
Place a bomb in a mug, add 1 cup of warm milk, stir until dissolved. Storage: airtight in the refrigerator 1 to 2 weeks, or frozen in a sturdy airtight container 1 to 2 months. Safety: contains milk powder.