The most common mistake when using a double boiler
A bain-marie is a simple way to melt chocolate or prepare delicate sauces like béarnaise or hollandaise, as long as the container does not touch the water.
According to bab.la, bain-marie means "water bath," and that's exactly what it is: a pot or container with food suspended over another pot of simmering water.
Melting or heating chocolate or an egg-based sauce is tricky because both can burn or curdle easily. A double boiler reduces this risk because the water comes between the food and the direct heat.
The most common mistake is letting the bottom of the container touch the water. According to MasterClass, a bain-marie works with steam, that is, with indirect heat. If the bottom touches the water, it receives direct heat and the food can overcook.
To prevent this, don't overfill the bottom pot, although the water will evaporate and you should keep an eye on it. Occasionally, lift the top pot to check that there are at least two and a half centimeters of water left. If not, remove the lid, add water to the bottom pot, and let it heat gently again. According to the Chicago Tribune, the water shouldn't boil, but rather be kept at a gentle simmer to create enough steam without overcooking.
To improvise this, all you need is a saucepan and a heat-resistant glass or stainless steel container that fits snugly on top of it, with water in the bottom but not touching the water. Rachael Ray uses this trick to keep mashed potatoes warm.
