Or you could try the alternative method, where you put an unopened can of sweetened condensed milk in a saucepan, add water, and boil for a certain amount of time (a while, as best as I remember). If it doesn't blow up, sending metal shrapnel all over the kitchen, you have an exquisite can of dulche y leche.
I only got away with doing it once when I was a kid. The can didn't blow up but my mother did when she discovered my - - - science experiment.