Evaporated milk is milk that has been cooked down to allow some of the water content to evaporate. The concentrate is canned, and the result is a heavier tasting milk with a slightly toasted or caramelized flavor. If you don't have any, make your own: To produce 1 cup of evaporated milk, simmer 2 1/4 cups of regular milk down until it becomes 1 cup.
In many recipes, evaporated milk may also be replaced with a combination of whole milk and half-and-half. For 1 cup of evaporated milk, use 3/4 cup whole milk and 1/4 cup half-and-half.
For more information on ingredient substitutions, see our Ingredient Substitutions guide.