01 - Place chopped chocolate in a microwave-safe bowl. Microwave in 30-second intervals, stirring after each, until fully smooth.
02 - Using a pastry brush or small spoon, evenly coat silicone half-sphere molds with the melted chocolate. Refrigerate for 10 minutes. Apply a second coat and chill until set, about 15 minutes.
03 - In a mixing bowl, combine hot cocoa mix, crushed peppermint candies or baking chips, and peppermint extract.
04 - Carefully remove set chocolate shells from the molds.
05 - Add 1 tablespoon cocoa mix, 1 tablespoon mini marshmallows, and a pinch of crushed peppermint to half of the shells.
06 - Warm a plate in the microwave. Lightly press the edge of an empty shell half onto the warm plate to soften, then immediately press onto a filled shell to seal. Repeat for remaining shells.
07 - Drizzle with melted white chocolate and sprinkle with extra crushed peppermint candies, if desired. Allow bombs to set completely.
08 - Place a cocoa bomb in a mug. Pour 1 cup (8 fl oz) hot milk over the bomb and stir until fully dissolved.