it is done on a water bath, without the can, in the oven. i sense a better tasting product, deeply floral, and without any traces of metallic canned taste. perhaps this is how it is done in rural south america, where canning or pressure cookers aren’t widely available. the method is easy, just takes a few hours of waiting time. i like when i am preheating the oven to bake bread.
the oven method is also SAFE. on the other hand, you may have heard horror stories about heating an unopened can of milk to make dulce de leche: it can explode. unless it happens to yourself or to a close friend of yours, you won’t believe it. this happened to a close friend of mines: click here.