In a small, microwave-safe bowl, melt 2 cups of chopped chocolate or chocolate chips in 15-second increments, stirring in between (it's important not to overheat the chocolate). You can also use the doubled boiler method which is even better but requires more work.
Take the molds, and spoon about 2 tablespoons of melted chocolate into each half-sphere. And then using a pastry brush or even the back of a spoon, just spread the chocolate around the sphere so that it's well coated. You need to have a good coating so that the chocolate bombs are not fragile.
Chill the half-spheres - Transfer the molds to the freezer for 15 minutes to solidify. Once set, gently and quickly remove from the molds. The heat of your hands can cause the chocolate to melt, so do this quickly.
It is best to decorate half of the half-spheres at this stage. Lay them on a tray or plate face down, and drizzle with melted chocolate and immediately sprinkle with multi-colored mini chocolate chips or any decoration you're using (before the drizzle hardens).
Return to the freeze for 5-10 minutes to make sure that the drizzle is hardened.
Take the plain half-spheres, and fill each with 1 tablespoon of hot cocoa mix, top with one piece of cosmic brownie if using, and a few mini marshmallows.
And finally to seal, warm up a small microwave-safe plate in the microwave just for 30-45 seconds. And lay each decorated empty half-sphere on the plate for a couple of seconds until it starts to melt and create a "glue", then connect it with the corresponding filled half sphere. Repeat with the remaining.
Make Hot Chocolate
Add one hot chocolate bomb to a mug, then pour about 6oz (175ml) of warm milk over the cocoa bomb and the shell will start melting and releasing the mini marshmallows and brownie. Use a spoon to stir the hot chocolate until it's nice and creamy.
Feel free to add even more mini marshmallows to the mug, and a drizzle of chocolate syrup if you're feeling fancy!
It's important that you don't overheat the chocolate. When melting the chocolate in the microwave, do so in 15 increments. For better results, use the double boiler method.
If you substitute the chocolate with chocolate melts, they will melt smoothly and look better but won't taste as good.
To avoid getting fingerprints on the cocoa bombs, wear food-safe gloves when working with the chocolate.
Store in a plastic bag or airtight container for up to 2 weeks at room temperature or in the fridge.
Hot Chocolate Bomb Flavors
Salted caramel: Add a little bit of salted caramel in the cocoa bomb or use caramel chips, then sprinkle the cocoa bomb with flaky sea salt.
Gingerbread: Use white chocolate for the cocoa bomb, add gingerbread spice or syrup inside the cocoa bomb. Sprinkle with crumbled gingerbread.
Birthday cake: Use white chocolate, add a drop of vanilla extract and mix in colorful sprinkles. Decorate with a drizzle of white chocolate and extra colorful sprinkles.
Peppermint: Add crushed peppermint candy inside the cocoa bombs, and sprinkle with more on the outside after the chocolate drizzle.
Mocha: Add a teaspoon of Instant coffee inside the cocoa bomb.
S'mores: You can lightly toast the mini marshmallows before placing them in the cocoa bombs, and add some crushed graham crackers inside the cocoa bomb, and to sprinkle the outside.
Oreo: Crushed some Oreos and place inside the cocoa bomb, and sprinkle the outside.