Via a hole in the handle, you fill the chamber with water, set it on a burner, and wait for a whistle to signal that the water is boiling. You then turn down the heat and add ingredients to melt or cook gently over the indirect heat of simmering water. I liked how it melted chocolate with no scorching and delivered even, low heat for cooking a hollandaise sauce. It’s also convenient that the water is sealed in its own compartment, preventing any accidental drips (water can cause chocolate to seize up). The compact, easy-to-store double boiler costs $40 at Cooking.com.
