In a bowl, mix the sugar and cocoa powder until fully combined. Set aside
Place chocolate chips in a microwave-safe bowl and microwave for 30 seconds. Stir thoroughly, scraping the sides and bottom of the bowl. Continue microwaving in 20-second intervals, stirring after each, until chocolate is completely melted and smooth
Using a spoon or paintbrush, coat the inside of the sphere mold with a layer of melted chocolate, making sure to cover the entire surface, including the edges. Once fully coated, transfer the mold to the refrigerator and chill for 10 minutes
After chilling, remove the mold from the fridge and apply a second layer of chocolate, repeating the same process. Return the mold to the fridge for an additional 20 minutes to set
Once the chocolate spheres are firm, gently remove them from the molds. Fill half of the spheres with chocolate milk powder and mini marshmallows
Place one empty chocolate sphere half on a warm plate to slightly soften the edges. Gently press it onto the filled half and hold for a few seconds to seal. Decorate with melted chocolate, sprinkles, or candies. Let the sphere set for about 10 minutes
To serve, place the hot chocolate bomb in a mug and pour hot milk or water over it. Stir well to melt the bomb and enjoy a rich, creamy hot chocolate treat!
