Preparation Steps

• Set up a sealing surface: Warm a small nonstick skillet over low heat for 1 minute, then turn it off. Alternative: Microwave 3/4 cup water in a heatproof measuring cup until steaming and set a plate on top to warm.
• Melt the chocolate using a seed-and-stir method. Place about 6 oz of the chopped chocolate in a microwave-safe bowl and heat at 60% power in 30-second bursts, stirring between each. When smooth, stir in the remaining 3 oz until glossy and fluid.
• First coat: Spoon a little melted chocolate into each mold cavity and use the back of a spoon to paint it up the sides. Tap the mold to release air bubbles. Refrigerate 8–10 minutes until set.
• Second coat: Add more chocolate to reinforce thin spots, especially around the rims. Chill again for 10–12 minutes until fully firm.
• Unmold the shells gently. Level the edges by touching the cut side of each half-sphere to the warm skillet or warmed plate for 1–2 seconds.
• Fill the bottoms: Set 6 shells in cupcake liners. Add about 1 heaping tablespoon hot chocolate mix and a few mini marshmallows to each; add a tiny pinch of sea salt if using. Let the filled shells rest 2 minutes so the chocolate relaxes (reduces cracking).
• Seal: Warm the rim of an unfilled top shell on the skillet or plate for 1–2 seconds and press onto a filled half to close. If needed, swipe a little melted chocolate along the seam. Refrigerate 12–15 minutes to set.
• Finish and garnish: Re-melt a couple tablespoons of leftover chocolate in short bursts until fluid. Drizzle over the bombs and top with sprinkles or shaved chocolate. Let stand 5–10 minutes to firm up.
• To serve: Place one bomb in a mug and pour 8–10 fl oz very hot milk over it. Stir until the shell melts and the cocoa is combined.