Without a double boiler on hand, melting chocolate can be tricky process. Using the wrong container for melting chocolate can lead to sticking, burning and other all around un-tasty results. Luckily, with some improvising you can fashion your own makeshift double broiler.
Fill the larger pan about 1/3 full with water. The water will keep the smaller vessel from overheating, as overheating will prevent the chocolate from melting properly.
Insert the smaller vessel into the cooking pan filled with water. Smaller saucepans are a good choice, as are mason jars or any other container large enough to contain the chocolate and sturdy enough to withstand the heat from the stove top.
Turn the boiler on a medium heat setting.
Fill the smaller vessel with the chocolate. Until you know how the volume will change with melting, add the chocolate slowly and in increments chocolate so the container or pan doesn't overflow.
While heating, slowly stir the chocolate. As the water in the larger pan warms up, it will warm and melt the chocolate in the smaller vessel. Do not cover either container, and keep the temperature on low heat, to prevent scorching the chocolate. The water in the larger pan should not reach a boil.
As it's melting, continue to stir the chocolate to ensure that it's heated evenly.
Remove the container of chocolate from the hot stove and allow it to cool.