01 - Place semi-sweet or dark chocolate in a heatproof bowl over a pot of simmering water and stir until fully melted and smooth.
02 - Spoon about 1 tablespoon of melted chocolate into each cavity of a silicone sphere mold (2.5–2.75 in diameter). Use a brush or back of a spoon to coat the sides evenly. Chill in the refrigerator for 10 minutes.
03 - Repeat the coating process to ensure sturdy shells and chill for another 10 minutes until set.
04 - Gently remove the hardened chocolate shells from the molds.
05 - Place 1 tablespoon hot cocoa mix, a handful of mini marshmallows, and a sprinkle of crushed peppermint candies into 6 shells.
06 - Warm a plate slightly. Press the edge of an empty shell onto the warm plate for a few seconds to soften, then immediately press it over a filled shell and seal gently. Repeat for all bombs.
07 - Drizzle with melted white chocolate and sprinkle with extra crushed peppermint candies if desired. Allow to set.
08 - Place a cocoa bomb in a mug and pour 1 cup (250 ml) of hot milk over it. Stir well and enjoy.