Combine hot cocoa mix and miniature marshmallows together in a small bowl. Line a small baking sheet with parchment paper. Set aside. 

Melt the chocolate: Bring a medium sized pot, halfway filled with water to a simmer over low heat. Place a heat safe bowl that fits in the top of the pan without touching the water atop the warming pan. Add the chocolate chips to the bowl. Stir until the chips are melted and can be stirred smooth. Remove the chocolate from the heat, but keep water on the stove for later. 

Form the molds: Add a heaping spoonful of the melted chocolate to each of the chocolate molds, using the spoon to spread the chocolate evenly throughout the mold, making sure to get it up the sides. Save the extra chocolate for decorating. 

Freeze: Place the molds in the freezer for 10-15 minutes, or until chocolate is completely set. 

Fill the Molds: Once the chocolate is set, carefully remove the chocolate from the molds and place them on the prepared baking sheet. Flip half of the molds over, and fill each of them with the cocoa/marshmallow mixture. Add ½ teaspoon of sprinkles if desired. 

Seal the molds: Take half of the molds and place them on another baking sheet, edges down. Set over the pot of simmering water, until the edges begin to melt. Using gloved hands, as to not leave fingerprints behind, place the empty half atop the filled half sealing the molds with the melted chocolate edges. *work quickly, the warmth of your fingers will melt the chocolate.

Decorate: Using leftover melted chocolate drizzle and decorate the molds. Can use melted white chocolate, peanut butter or caramel chips for something different. Dust with sprinkles for holiday chocolate bombs!

Serve: Pour 1 cup of very hot milk into a large mug, Gently add the bomb and stir into milk.