Sure, I could buy evaporated milk in a little tin at the supermarket and keep it in my pantry until I need it. But I don't. So whenever a recipe calls for evaporated milk, I'm always scrambling to find some kind of evaporated milk substitute in a pinch. And it's hard to find an evaporated milk substitute that has the same consistency and slightly caramelized flavor as the original. But, fortunately for me, and anyone else who doesn't think to buy evaporated milk before they might need it, the best evaporated milk substitute is also the easiest—and there's no pre-purchased can required. You can actually make DIY evaporated milk, and although it's time consuming, it's probably the best substitute for canned evaporated milk out there.
The first step to learning how to make evaporated milk at home is understanding what is evaporated milk. As Gabrielle Van Tassel explained for Extra Crispy, evaporated milk is "produced by cooking regular milk at a low temperature so that 60 percent of the water content evaporates." (In essence, the main difference between evaporated milk and sweetened condensed milk is sugar—it's added into the latter, not the former.)
That means all you need to make evaporated milk at home is some milk, a saucepan, a stove, and a stirring utensil. And I'd be willing to bet good money that if you're making a recipe that calls evaporated milk, you already have all of these in your kitchen.
The tricks for making evaporated milk at home are getting the ingredient ratio right and also making sure you've evaporated enough water. According to a recipe for an evaporated milk substitute from MyRecipes, "To produce 1 cup of evaporated milk, simmer 2¼ cups of regular milk down until it becomes 1 cup." That sounds simple enough, but Jessie Oleson Moore has some more in-depth instructions for making evaporated milk at home on Craftsy. For instance, she recommends stirring constantly, so as to prevent burning. She also notes that there's a good chance you'll find milks solids at the bottom of the pan. But don't freak out. "This is totally normal; by straining the milk after it has reduced to your desired amount, you can remove these bits from the liquid."
If you don't want to deal with stirring the milk until it's condensed, you can make evaporated milk in a slow cooker. In her blog In Jennie's Kitchen, Jennifer Perillo has a recipe making evaporated milk in this low, slow, and totally hands-off method. Place 3¾ cups of milk in a slow cooker, and let it do its magic. The only downside? It takes about eight to ten hours, which doesn't exactly bode well for bakers who are in a rush. (Namely, me.)
You can also use a combination of 1½ cups of powdered milk and 1¼ cups of water to create a creamy paste with something that's got the consistency of evaporated milk. But let's be real. Chances are good that if you don't have cans of evaporated milk in your kitchen, you don't have powdered milk. And after that, the only evaporated milk substitute that's left is to mix together some heavy cream and whole milk—but we all know that won't give your baked good the same consistency as some good evaporated milk.
So maybe instead of trying to find an evaporated milk substitute, I should stock up on cans of evaporated milk the next time I'm at the supermarket and try to be prepared for once.