01 - Gently melt the chocolate in a microwave or double boiler, stirring frequently until smooth.
02 - Use a pastry brush or spoon to coat the inside of 12 half-sphere silicone molds (2-inch diameter) with a thick, even layer of melted chocolate.
03 - Refrigerate the chocolate-coated molds for 10 minutes to set the shells.
04 - Add a second thick layer of chocolate to the molds and chill for an additional 10 minutes for sturdiness.
05 - Carefully unmold the hardened chocolate shells.
06 - Fill 6 chocolate halves with 1 tbsp cocoa mix, 0.35 oz mini marshmallows, and optionally a few chocolate chips or sprinkles.
07 - Warm a small plate in the microwave; gently press the edge of an empty shell onto the warm plate to slightly melt it, then immediately press it onto a filled half to seal. Repeat for all cocoa bombs.
08 - Drizzle melted white chocolate over the sealed bombs and add festive sprinkles. Allow to set at room temperature.