To have a better control on the temperature of the ingredient that we want to melt, for a better result we use this technique called “Bagnomaria” (or “water bath” in English).
How to Use the Bagnomaria / Water Bath Cooking Technique:
We need 2 pots — a bigger one, filled half way with water, and a smaller one, on top of it touching the water — with the ingredient inside. This way the water in the larger pot surrounds the small pot and gently releases the heat for a better control on the result.
Use high heat at the beginning and then, when the water starts boiling, turn it down to medium/low and add the ingredient. Stir until melted.
This is a great way to melt, or heat ingredients without worrying to much about burning them, because of the slow transfer of the heat to the ingredient. This technique reaches a temperature of 185 – 203 degrees, very manageable.
The technique is time-consuming, but it is widely used in confectionery. It lets you have more control over the degree of preparation of certain compounds that otherwise would suffer extreme changes in violent heat, as chocolate, eggs (ex. custard for ice cream), honey, or sugar.
In the example of the photos I am melting chocolate and mixing it with butter. This is just one example of the use of this useful technique. Enjoy.