How it works
A double boiler is a way to use indirect heat to cook delicate foods. You can use it to melt chocolate, cook sauces containing milk and cheese or make custards — pretty much anything that could easily burn. You can also use them to keep foods warm without overcooking anything.
A pre-fab double boiler has two pots. In one pot (the larger bottom pot) you heat water, which when heated or boiled, lets off steam, which cooks delicate foods without burning or scorching. A second pan, where you’ll actually do the cooking, fits inside that. The benefit to a pre-fab model is that they come with a lid that fits both pots.
But for most foods that take to double boiler cooking, you don’t need a lid, so it’s only a good purchase if you’ll need a lid and use it frequently. You can also make your own double boiler by fitting a glass or metal mixing bowl (one rated for the high heat of a dishwasher or microwave) into a large pot.
The bowl should fit snuggly atop the pot so it won’t move around too much and the bottom doesn’t go more than halfway in. A lid can be improvised using the lid of a large stockpot if necessary.
How to use a double boiler
Most people shy away from double boiler cooking because they’re worried about ruining their mixing bowls. So long as the mixing bowl is rated for high heat (as most glass models are), this won’t happen. Keep in mind, people who make preserves often directly boil Mason jars to sterilize them prior to adding fruits or veggies.
To create the indirect heat, add water to the bottom pan. The waterline shouldn’t touch the bottom of the bowl. The point here is to use the steam as indirect heat. Once the top bowl is hot, make sure you use tongs or a dry towel to grip it if necessary. It may be hot.
Unless otherwise directed by the recipe you’re using, don’t add any ingredients until the water has come to a boil. That’s why it’s nice to use a glass bowl — so you can always see what your water is doing.
Things you should know about a double boiler
- Chocolate should be heated in a double boiler, not a microwave, if the texture of the chocolate is important. The direct heat of the microwave (or a saucepan without a double boiler) will cause the chocolate to clump.
- You can reduce the risk of salmonella in hollandaise sauce by adding lemon juice. It prevents the proteins from coalescing, which creates a scrambled egg, when you heat them to at least 160 degrees F (to kill the salmonella (it also adds a nice tangy flavor!).
- You can use a double boiler to keep liquids used in candy making, soap making and candle making in a liquid state. You can also use it to keep soups and other foods warm without cooking them down further (which in a soup could thicken the broth and increase the saltiness).