In a mixing bowl, whisk together the sugar, cocoa powder, and salt. Set aside.

Fill a medium pot halfway with water. Bring the water to a simmer over low heat. Place a heat-safe bowl on top of the pot and add the chocolate chips. Stir the melting chocolate with a rubber spatula until smooth. Remove the bowl.

Add a heaping spoonful of the melted chocolate to each of the six chocolate molds, spreading the chocolate up the sides. Freeze the chocolate for 10 minutes, or until completely set.

Line a baking sheet with parchment paper. Once set, carefully remove the chocolate cups from the mold and place them on the lined baking sheet.

Flip over three of the molds to be filled. Fill each of the 3 halves with 2 tablespoons of hot cocoa mix, 1 tablespoon of crushed peppermint candies, and 5-6 mini marshmallows.

Place the other three halves, seam-side down, on a separate baking sheet. Place the sheet on top of the pot of warm water over low heat to slightly melt the rims of the molds.

With gloves on, cover each filled chocolate half with an empty half, sealing it. Decorate with any extra melted chocolate, remaining candies, or sprinkles.

Use immediately or within 24 hours, storing at room temperature. To serve, add a peppermint hot cocoa bomb to a mug and slowly pour about 1½ cups of hot milk or hot water over the bomb. Stir and enjoy!