Double boiling is when you cook or melt something with the heat from the steam of boiling water. It is slightly different from the steaming process whereby the food comes directly into contact with the steam. In double boiling, the steam does not touch the food, it merely heats up the bowl or pan in which the food is contained. To double boil something, you would need at least one saucepan or pot and one heat proof bowl. Ideally, the bowl should be large enough to sit on top of the pot or saucepan without going in and touching the water. You then fill up the saucepan with water (about one third or half full) and place the heatproof bowl on top. The bowl should not be touching the water underneath, but it should sit directly on the pot. Add the food you intend to double boil (like chocolate or cheese) and heat up the water to melt the chocolate or cheese. This method is typically used to temper chocolate, and for cooking items that are prone to burning when subjected to direct heat.