For most recipes and diets, one cup of half-and-half, whole milk or heavy cream is equivalent to one cup of evaporated milk. Evaporated milk is milk that has had about half its water evaporated off, leaving a thicker liquid.
People with dairy allergies or intolerance can use coconut milk in place of evaporated milk. Allow one full can of coconut milk to settle for about 30 minutes. Once the coconut cream rises to the top, simply skim it off and use the resulting liquid in a 1:1 ratio. Other dairy-free options include simmering three cups of rice or soy milk in a pan until it is reduced to one cup.