Preheat oven to 200°F (90°C) for 10 minutes to create a warm environment for melting chocolate

Melt chocolate in a double boiler or in a microwave-safe bowl in 30-second increments, stirring between each interval, until smooth

Prepare a silicone candy mold or a small cupcake liner by lightly spraying with cooking spray to ensure easy removal

Fill the mold or liner about 1/4 of the way with melted chocolate, then tap gently to remove air bubbles

Allow the chocolate to set at room temperature or in the refrigerator for about 10 minutes, until the edges start to harden

Fill the center of the chocolate shell with desired fillings, such as marshmallows or cocoa powder

Drizzle a small amount of melted chocolate over the fillings to seal the bomb

Refrigerate the hot cocoa bombs for at least 30 minutes to set the chocolate completely

Remove the bombs from the mold or liner and serve by dropping into a mug of hot milk, watching as it dissolves and releases the fillings