Q&A for How to Use a Double Boiler

Explosions can be cause by a lack of somewhere for the air pressure coming from the bottom part to go. Always leave a little area for the bottom to "breathe" so that pressure does not build up. When it has nowhere to go, it makes a place to go.

I wouldn't recommend it, as I don't see any benefit in preventing the rice from coming in more direct contact with the heat. While it's true that (after the initial boil) rice is simmered at a low temperature for 15-20 minutes (depending on the grain), the rice still needs that direct, high heat in order to cook more quickly and evenly. From my understanding, double boilers are meant for cooking delicate ingredients that are easy to overheat or burn (that are more fragile than rice), such as melting and tempering chocolate, whipped eggs, and other delicate ingredients.

I have made lemon meringue pie filling in a double boiler since I was a teenager. I bring the water to a boil and then turn the heat down to keep it simmering. It might take a little longer, but it won't burn when you cook it. This is especially useful if you have an electric or glass top stove! Stirring constantly while cooking your filling is still a good idea. (My 1960s recipe does have me cover the thickened mixture at the point where eggs yolks and sugar are added, and to let it cook for 10 minutes without stirring.)

When I use a double boiler, I would fill the bottom pot with about 1.5-2 inches of water, place a bowl (or the top portion of the double boiler) on top of the pot with water. Turn on the heat (medium works well for me) and allow steam to build in the bottom, then proceed as directed by the instructions.