Sweetened condensed milk is a dangerous thing. Open a can and have a spoon handy, and you have a snack for the rest of the day. It's full of milk flavor, plenty sweet, and just plain tasty. It can also be used for non-snacking purposes, if you're into that sort of thing.
It's pretty simple to make your own sweetened condensed milk, and I used the recipe from Almost Bourdain as my base. My only real change, aside from being a bit loose with the measurements, was to use some of my stash of dried whole milk instead of dried skim milk.
Using the dried whole milk may not have been the best idea, but it's what I had, and that's kind of the point of making sweetened condensed milk; like brown sugar, you're probably not going to do much better than what you get from the store. Well, unless you're trying something special, but more on that in a bit. Sweetened condensed milk is going to store just about as long as powdered milk will, so chances are that, if you're making it, it's because you have one ingredient and not the other.
Now, if you're fancy, you could try some tricks with the sweetened condensed milk. To continue the brown butter kick I've been on since Ideas in Food started posting crazy things to do with brown butter, it occurs to me that the milk solids in the sweetened condensed milk could be browned before combining with the sugar. This is different from Dulce de Leche, I believe, because you wouldn't get any caramelization with the sugar.
In any case, making sweetened condensed milk is awfully simple.
Measure out your butter, water, and sugar:
Melt on your fancy new gas range (or whatever; I understand if you didn't just buy a new home mostly because it has gas):
Take the mixture off the heat. Measure out some milk solids:
Mix in 4 batches:
Until it's all smooth:
Or, in my case, until it was fully combined but a bit grainy. I tried adding some water to smooth it out. It helped some, but not enough. It was not creamy smooth as sweetened condensed milk should be. Probably using the whole milk powder didn't do me any favors here.
Even with the graininess, it was plenty tasty. It had the milky, sweet flavor. But better than from a can? Not really. Handy if you're in the right bind, and maybe more awesome if you brown the milk solids in the butter before adding the sugar and water, but that's an experiment for another day.