I finally got up the nerve to boil a can of condensed milk, in order to make dulce de leche. I've always heard of this method, but been a little afraid to try it. Surprisingly, miracle or magic trick - it worked! I was sure I was going to blow up the kitchen. I still don't know if it's completely safe, but I read that as long as you keep the can completely covered with water, everything is fine.
I put the can of condensed milk on top of a metal ring in a deep heavy pot, so that the water could circulate completely around it. I filled the pot with enough water to cover the can by a couple of inches, and let the water simmer for 2 hours. Once the can had cooled enough to handle, I opened it and found thick, shiny, caramel, perfect dulce de leche. It was really amazing, and I'm not sure how it works. I thought some of the water had to evaporate away, especially because the dulce de leche is much thicker than the evaporated milk. But the can was very full. It was quite a transformation.
I still prefer the taste of the slowly stirred dulce de leche, flavored with cinnamon. But this is a great option when you don't have time to stand at the stove stirring for an hour.Dulce de Leche, Slow but Delicious Method (With Lots of Stirring)
Dulce de Leche, Double Boiler Method