Line a large baking sheet with parchment or wax paper. Set aside a medium cereal bowl, about 6 inches wide.
Inflate six 5-inch / 12 cm balloons to their normal size.
Place the chopped chocolate into a medium microwaveable bowl.
Melt chocolate slowly over a double boiler. Alternatively, microwave on medium power in 30-second intervals, stirring each time.
Spoon six tablespoon-size dollops of chocolate onto the prepared baking sheet about 6 inches / 15 cm apart.
Pour all the melted chocolate into cereal bowl.
Dip a balloon about 3 inches / 7 cm into the chocolate to coat, and gently press into a dollop on baking sheet. Repeat for remaining balloons.
Freeze for one hour or refrigerate 3 hours until solid.
Use a toothpick, cake tester or sharp paring knife to pop the balloon (see note).
Carefully peel away any pieces of balloon, and then lift the bowls off the baking sheet.