Please consider a few things before you begin this project. First, not every balloon works. They don't always release. If you can find the strong punching bag type balloon, choose that one. Some people are allergic to latex so be aware that most balloons are made from latex. Inflate the balloon. Secure it closed with a ribbon (you will need to untie this later). Dip the bottom of the balloon in the dark chocolate. This will create a base. Set the wet chocolate onto a parchment paper-lined surface. Make sure it stands straight. Let the chocolate set until firm. Place dark chocolate in a cornet. The next step will be easier if you have an assistant. Have the assistant hold the balloon horizontally in front of you while you pipe chocolate lines from top to bottom all the way around the surface. When complete, drizzle more lines diagonally across the existing lines. Apply a bit more chocolate near the top opening and near the bottom to provide extra support. This will form a bird cage effect. Let the chocolate set. When the chocolate begins to harden, release a little bit of the air from the balloon, but just enough so the balloon retracts slightly (about 1/8-inch from the outside). Carefully set the chocolate covered balloon aside. Depending on your room temperature, it will take a good 10 minutes to set. To make the balloon flowers, inflate 10 small balloons and close them with ribbons. Your presentation will be more interesting if you inflate them to different degrees to make different sized flowers. Dip each balloon anywhere from 1 to 3 times to create a different number of petals on each. To accomplish this, dip the balloon once, spin it slightly, dip it again, etc. Set each dipped balloon on a parchment-lined sheet pan and allow the chocolate to set. When set, pop the balloon and remove the deflated balloon from the flower. Use cocoa butter paints to decorate the insides of the flowers. Let the paint set. If you made different sizes, you can layer the balloon flowers by setting one inside another. Use chocolate to "glue" them together. Slowly deflate the large balloon that is inside the large chocolate cage by untying its ribbon. Carefully pull the deflated balloon through the hole at the top. Use tempered chocolate to "glue" the chocolate flowers onto the large cage. Reserve one to cover the hole at the top. Your guests will certainly be fascinated by your creation.
From Dessert Circus, Extraordinary Desserts You Can Make at Home, by Jacques Torres
How to Temper Chocolate:
Chocolate is tempered so that after it has been melted, it retains its gloss and hardens again without becoming chalky and white (that happens when the molecules of fat separate and form on top of the chocolate). There are a variety of ways to temper. One of the easiest ways to temper chocolate is to chop it into small pieces and then place it in the microwave for 30 seconds at a time on high power until most of the chocolate is melted. Be very careful not to overheat it. (The temperature of dark chocolate should be between 88 and 90 degrees F, slightly warmer than your bottom lip. It will retain its shape even when mostly melted. White and milk chocolates melt at a temperature approximately 2 degrees F less because of the amount of lactose they contain.) Any remaining lumps will melt in the chocolate's residual heat. Use an immersion blender or whisk to break up the lumps. Usually, chocolate begins to set, or crystallize, along the side of the bowl. As it sets, mix those crystals into the melted chocolate to temper it. A glass bowl retains heat well and keeps the chocolate tempered longer. Another way to temper chocolate is called seeding. In this method, add small pieces of unmelted chocolate to melted chocolate. The amount of unmelted chocolate to be added depends on the temperature of the melted chocolate, but is usually 1/4 of the total amount. It is easiest to use an immersion blender for this, or a whisk. The classic way to temper chocolate is called tabliering. Two thirds of the melted chocolate is poured onto a marble or another cold work surface. The chocolate is spread out and worked with a spatula until its temperature is approximately 81 degrees F. At this stage, it is thick and begins to set. This tempered chocolate is then added to the remaining non-tempered chocolate and mixed thoroughly until the mass has a completely uniform temperature. If the temperature is still too high, part of the chocolate is worked further on the cold surface until the correct temperature is reached. This is a lot of work, requires a lot of room, and makes a big mess. A simple method of checking tempering, is to apply a small quantity of chocolate to a piece of paper or to the point of a knife. If the chocolate has been correctly tempered, it will harden evenly and show a good gloss within a few minutes.